Amoxicillin

Name: Amoxicillin

Side effects

The following are discussed in more detail in other sections of the labeling:

  • Anaphylactic reactions [see WARNINGS AND PRECAUTIONS]
  • CDAD [see WARNINGS AND PRECAUTIONS]

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

The most common adverse reactions (> 1%) observed in clinical trials of AMOXIL capsules, tablets or oral suspension were diarrhea, rash, vomiting, and nausea.

Triple therapy: The most frequently reported adverse events for patients who received triple therapy (amoxicillin/clarithromycin/ lansoprazole) were diarrhea (7%), headache (6%), and taste perversion (5%).

Dual therapy: The most frequently reported adverse events for patients who received double therapy amoxicillin/lansoprazole were diarrhea (8%) and headache (7%). For more information on adverse reactions with clarithromycin or lansoprazole, refer to the Adverse Reactions section of their package inserts.

Postmarketing or Other Experience

In addition to adverse events reported from clinical trials, the following events have been identified during postmarketing use of penicillins. Because they are reported voluntarily from a population of unknown size, estimates of frequency cannot be made. These events have been chosen for inclusion due to a combination of their seriousness, frequency of reporting, or potential causal connection to AMOXIL.

  • Infections and Infestations: Mucocutaneous candidiasis.
  • Gastrointestinal: Black hairy tongue, and hemorrhagic/pseudomembranous colitis.
    Onset of pseudomembranous colitis symptoms may occur during or after antibacterial treatment [see WARNINGS AND PRECAUTIONS].
  • Hypersensitivity Reactions: Anaphylaxis [see WARNINGS AND PRECAUTIONS]. Serum sickness-like reactions, erythematous maculopapular rashes, erythema multiforme, Stevens-Johnson syndrome, exfoliative dermatitis, toxic epidermal necrolysis, acute generalized exanthematous pustulosis, hypersensitivity vasculitis, and urticaria have been reported.
  • Liver: A moderate rise in AST and/or ALT has been noted, but the significance of this finding is unknown. Hepatic dysfunction including cholestatic jaundice, hepatic cholestasis and acute cytolytic hepatitis have been reported.
  • Renal: Crystalluria has been reported [see OVERDOSAGE].
  • Hemic and Lymphatic Systems: Anemia, including hemolytic anemia, thrombocytopenia, thrombocytopenic purpura, eosinophilia, leukopenia, and agranulocytosis have been reported. These reactions are usually reversible on discontinuation of therapy and are believed to be hypersensitivity phenomena.
  • Central Nervous System: Reversible hyperactivity, agitation, anxiety, insomnia, confusion, convulsions, behavioral changes, and/or dizziness have been reported
  • Miscellaneous: Tooth discoloration (brown, yellow, or gray staining) has been reported. Most reports occurred in pediatric patients. Discoloration was reduced or eliminated with brushing or dental cleaning in most cases.

Overdose

In case of overdosage, discontinue medication, treat symptomatically, and institute supportive measures as required. A prospective study of 51 pediatric patients at a poison-control center suggested that overdosages of less than 250 mg/kg of amoxicillin are not associated with significant clinical symptoms.

Interstitial nephritis resulting in oliguric renal failure has been reported in a small number of patients after overdosage with amoxicillin1.

Crystalluria, in some cases leading to renal failure, has also been reported after amoxicillin overdosage in adult and pediatric patients. In case of overdosage, adequate fluid intake and diuresis should be maintained to reduce the risk of amoxicillin crystalluria.

Renal impairment appears to be reversible with cessation of drug administration. High blood levels may occur more readily in patients with impaired renal function because of decreased renal clearance of amoxicillin. Amoxicillin may be removed from circulation by hemodialysis.

Uses of Amoxicillin

Amoxicillin is a prescription antibiotic used in the treatment of the following:

  • infections of the ear, nose, and throat
  • infections of the reproductive organs
  • infections of the urinary tract
  • infections of the skin and skin structure
  • infections of the lower respiratory tract
  • gonorrhea
  • infection by H. pylori (type of bacterium) to reduce the risk of duodenal ulcer recurrence

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

Amoxicillin Brand Names

Amoxicillin may be found in some form under the following brand names:

  • Amoclan

  • Amoxi Drop

  • Amoxi-tabs

  • Amoxicot

  • Amoxil

  • Augmentin

  • Biomox

  • Clavamox

  • Dispermox

  • Moxatag

  • Moxilin

  • Senox

  • Trimox

  • Wymox

Amoxicillin Drug Class

Amoxicillin is part of the drug class:

  • Penicillins with extended spectrum

Amoxicillin Dosage and Administration

Administration

Oral Administration

Administer orally without regard to meals.1 4 10 22 29 38 40

Following reconstitution, the required amount of oral suspension should be placed directly on the child’s tongue for swallowing.1 Alternatively, the required amount of suspension can be added to infant formula, milk, fruit juice, water, ginger ale, or cold drinks and these fluids taken immediately and completely consumed.1

For most infections, continue therapy for at least 48–72 hours after patient becomes asymptomatic or evidence that the infection is eradicated is obtained.1 The drug should be given for at least 10 days for treatment of infections caused by S. pyogenes (group A β-hemolytic streptococci).1

Reconstitution

Reconstitute oral suspension at the time of dispensing.1 Tap bottle to thoroughly loosen powder and then add the amount of water specified on the bottle in 2 portions; agitate vigorously after each addition.1

Agitate suspension well prior to administration of each dose.1

Dosage

Available as the trihydrate;1 dosage expressed in terms of anhydrous amoxicillin.1

Pediatric Patients

Neonates and infants ≤12 weeks (3 months) of age can receive amoxicillin in a dosage up to 30 mg/kg daily given in divided doses every 12 hours.1

Pediatric dosage specified below is for those >3 months of age weighing <40 kg.1

Children weighing ≥40 kg should receive usual adult dosage.1

Otitis Media Treatment of Acute Otitis Media (AOM) Oral

80–90 mg/kg daily given in 2 or 3 divided doses† recommended by AAP, AAFP, CDC, and others.190 200 201 205 215 244

Usual duration is 10 days;190 200 201 205 215 optimal duration is uncertain.244 AAP and AAFP recommend 10 days in those <6 years of age and in those with severe disease and state 5–7 days may be appropriate in those ≥6 years of age with mild to moderate AOM.244

Prevention of Recurrent AOM† Oral

20 mg/kg daily given in 1 or 2 divided doses has been used.214 220

Pharyngitis and Tonsillitis Oral

45 mg/kg daily in 2 divided doses or 40 mg/kg daily in 3 divided doses for 10 days.1 39 108 109

50 mg/kg once daily35 or 750 mg once daily for 10 days†.110

Follow-up throat cultures after treatment of pharyngitis and tonsillitis not indicated in asymptomatic patients,190 240 242 but recommended 2–7 days after treatment in those who remain symptomatic, develop recurring symptoms, or have a history of rheumatic fever and are at unusually high risk for recurrence.240 242

Ear, Nose, and Throat Infections Oral

25 mg/kg daily in divided doses every 12 hours or 20 mg/kg daily in divided doses every 8 hours for mild to moderate infections per manufacturer.1

45 mg/kg daily in divided doses every 12 hours or 40 mg/kg in divided doses every 8 hours for severe infections per manufacturer.1

Respiratory Tract Infections Oral

45 mg/kg daily in divided doses every 12 hours or 40 mg/kg daily in divided doses every 8 hours for mild, moderate, or severe lower respiratory tract infections.1

Skin and Skin Structure Infections Oral

25 mg/kg daily in divided doses every 12 hours or 20 mg/kg daily in divided doses every 8 hours for mild to moderate infections.1

45 mg/kg daily in divided doses every 12 hours or 40 mg/kg daily in divided doses every 8 hours for severe infections or those caused by less susceptible bacteria.1

Urinary Tract Infections (UTIs) Oral

25 mg/kg daily in divided doses every 12 hours or 20 mg/kg daily in divided doses every 8 hours for mild to moderate infections.1

45 mg/kg daily in divided doses every 12 hours or 40 mg/kg daily in divided doses every 8 hours for severe infections or those caused by less susceptible bacteria.1

Gonorrhea Oral

Prepubertal children ≥2 years of age: 50 mg/kg as a single dose given with a single dose of probenecid (25 mg/kg).1

No longer recommended for gonorrhea by the CDC or other experts.94 189

Lyme Disease Oral

25–50 mg/kg daily (up to 2 g daily) in 2–3 divided doses for 14–21 days for treatment of early localized or early disseminated Lyme disease†.95 179 181 182 185 190 238

50 mg/kg daily in 3 divided doses for 14–28 days for mild Lyme carditis95 179 181 182 185 186 or for 28 days for Lyme arthritis (without associated neurologic disease).95 190 181 185 186 232 238

Prevention of Bacterial Endocarditis Patients Undergoing Certain Dental, Oral, Respiratory Tract, or Esophageal Procedures Oral

50 mg/kg given 1 hour prior to the procedure.96

Patients Undergoing Certain GU or GI (except Esophageal) Procedures Oral

50 mg/kg as a single dose given 1 hour prior to the procedure for moderate-risk patients.96

For high-risk patients, give an initial IM or IV dose of ampicillin with IM or IV gentamicin within 30 minutes of starting the procedure followed by 25 mg/kg of amoxicillin 6 hours later.96

Prevention of S. pneumoniae Infections in Asplenic Individuals† Oral

20 mg/kg daily in children with anatomic or functional asplenia.190

In infants with sickle cell anemia, initiate prophylaxis as soon as diagnosis is established (preferably by 2 months of age);190 74 continue until approximately 5 years of age.190 74 243 Appropriate duration in children with asplenia from other causes unknown;190 some experts recommend that asplenic children at high risk receive prophylaxis throughout childhood and into adulthood.190

Anthrax Postexposure Prophylaxis Oral

80 mg/kg daily (maximum 1.5 g daily) given in divided doses every 8 hours for 60 days for postexposure prophylaxis following exposure to B. anthracis spores (inhalational anthrax)†.190 231 233 239

500 mg every 8 hours for 60 days in those weighing ≥20 kg.231

Use only if penicillin susceptibility is confirmed.190 228

Inhalational Anthrax Oral

80 mg/kg daily (maximum 1.5 g daily) given in divided doses every 8 hours for 60 days for treatment of inhalational anthrax in a mass-casualty setting†.231

500 mg every 8 hours for 60 days for those weighing ≥20 kg.231

Cutaneous Anthrax Oral

80 mg/kg daily (maximum 1.5 g daily) given in divided doses every 8 hours for treatment of uncomplicated cutaneous anthrax†.234 231

Treat for 60 days if cutaneous anthrax occurred as the result of exposure to aerosolized anthrax spores;231 234 7–10 days may be adequate if it occurred as the result of natural or endemic exposure to anthrax.231 234

Adults

Pharyngitis and Tonsillitis Oral

500 mg 3 times daily39 or 750 mg once daily† for 10 days.35 110

Follow-up throat cultures after treatment of pharyngitis and tonsillitis not indicated in asymptomatic patients,190 240 242 but recommended 2–7 days after treatment in those who remain symptomatic, develop recurring symptoms, or have a history of rheumatic fever and are at unusually high risk for recurrence.240 242

Ear, Nose, and Throat Infections Oral

500 mg every 12 hours or 250 mg every 8 hours for mild to moderate infections per manufacturer.1

875 mg every 12 hours or 500 mg every 8 hours for severe infections or those caused by less susceptible bacteria per manufacturer.1

Respiratory Tract Infections Oral

875 mg every 12 hours or 500 mg every 8 hours for mild, moderate, or severe lower respiratory tract infections.1

Skin and Skin Structure Infections Oral

500 mg every 12 hours or 250 mg every 8 hours for mild to moderate infections.1

875 mg every 12 hours or 500 mg every 8 hours for severe infections or those caused by less susceptible bacteria.1

Urinary Tract Infections (UTIs) Oral

500 mg every 12 hours or 250 mg every 8 hours for mild to moderate infections.1

875 mg every 12 hours or 500 mg every 8 hours for severe infections or those caused by less susceptible bacteria.1

Gonorrhea Oral

3 g as a single dose.1

No longer recommended for gonorrhea by the CDC or other experts.94 189

Typhoid Fever Oral

100 mg/kg daily or 1–1.5 g every 6 hours for 14 days.6

Helicobacter pylori Infection and Duodenal Ulcer Disease Oral

1 g 2 times daily for 10 or 14 days given in conjunction with clarithromycin and either lansoprazole or omeprazole (triple therapy).1 168 172 173 174

1 g 3 times daily for 14 days given in conjunction with lansoprazole (dual therapy).1 168

Lyme Disease Oral

500 mg 3 times daily for 14–21 days for treatment of early localized or early disseminated Lyme disease†.95 238

500 mg 3 times daily for 14–28 days for mild Lyme carditis95 179 181 182 185 186 or for 28 days for Lyme arthritis (without associated neurologic disease).95 190 181 185 186 232 238

Chlamydial Infections Oral

500 mg 3 times daily for 7 days for treatment of chlamydial infections in pregnant women†.94 189 190

Repeat testing (preferably by culture) recommended 3 weeks after completion of treatment.94

Prevention of Bacterial Endocarditis Patients Undergoing Certain Dental, Oral, Respiratory Tract, or Esophageal Procedures Oral

2 g given 1 hour prior to the procedure.96

Patients Undergoing Certain GU or GI (except Esophageal) Procedures Oral

2 g given 1 hour prior to the procedure in moderate-risk patients.96

For high-risk patients, give an initial IM or IV dose of ampicillin with IM or IV gentamicin within 30 minutes of starting the procedure followed by 1 g of amoxicillin 6 hours later.96

Anthrax Postexposure Prophylaxis Oral

500 mg every 8 hours for 60 days for postexposure prophylaxis following exposure to B. anthracis spores†; use only if penicillin susceptibility confirmed.231 233 236

Inhalational Anthrax Oral

500 mg every 8 hours for 60 days for treatment of inhalational anthrax†.231

Cutaneous Anthrax Oral

500 mg every 8 hours for treatment of inhalational anthrax†.231

Treat for 60 days if cutaneous anthrax occurred as the result of exposure to aerosolized anthrax spores;231 234 7–10 days may be adequate if it occurred as the result of natural or endemic exposure to anthrax.231 234

Prescribing Limits

Pediatric Patients

Neonates and Infants ≤12 weeks (3 Months) of Age Oral

Maximum 30 mg/kg daily in divided doses every 12 hours.1

Prevention of Bacterial Endocarditis Oral

Dosage should not exceed adult dosage for prevention of bacterial endocarditis.96

Special Populations

Renal Impairment

Dosage adjustment necessary in severe renal impairment.1 6 41 82 83

Do not use 875-mg tablets in those with severe renal impairment and GFR <30 mL/minute.1

Dosage recommendations not available for pediatric patients with renal impairment.1

Dosage for Adults with Renal Impairment

GFR (mL/min)

Daily Dosage

10–30

250 or 500 mg every 12 hours depending on infection severity1

<10

250 or 500 mg every 24 hours depending on infection severity1

Hemodialysis Patients

250 or 500 mg every 24 hours depending on infection severity; with an additional dose both during and at the end of dialysis1

Commonly used brand name(s)

In the U.S.

  • Amoxicot
  • Amoxil
  • DisperMox
  • Moxatag
  • Moxilin
  • Trimox

In Canada

  • Amoxil Pediatric
  • Apo-Amoxi
  • Apo-Amoxi Sugar-Free
  • Gen-Amoxicillin
  • Med Amoxicillin
  • Novamoxin
  • Novamoxin Reduced Sugar
  • Nu-Amoxi
  • Riva-Amoxicillin
  • Scheinpharm Amoxicillin
  • Zimamox

Available Dosage Forms:

  • Tablet
  • Tablet, Chewable
  • Tablet for Suspension
  • Powder for Suspension
  • Tablet, Extended Release
  • Capsule

Therapeutic Class: Antibiotic

Pharmacologic Class: Penicillin, Aminopenicillin

Before Using amoxicillin

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For amoxicillin, the following should be considered:

Allergies

Tell your doctor if you have ever had any unusual or allergic reaction to amoxicillin or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Pediatric

Appropriate studies performed to date have not demonstrated pediatric-specific problems that would limit the usefulness of amoxicillin in children. However, newborns and infants 3 months of age and younger have incompletely developed kidney functions, which may need a lower dose of amoxicillin.

Geriatric

Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of amoxicillin in the elderly. However, elderly patients are more likely to have age-related kidney problems, which may require caution and an adjustment in the dose for patients receiving amoxicillin.

Pregnancy

Pregnancy Category Explanation
All Trimesters B Animal studies have revealed no evidence of harm to the fetus, however, there are no adequate studies in pregnant women OR animal studies have shown an adverse effect, but adequate studies in pregnant women have failed to demonstrate a risk to the fetus.

Breast Feeding

Studies in women suggest that this medication poses minimal risk to the infant when used during breastfeeding.

Interactions with Medicines

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking amoxicillin, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using amoxicillin with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Chlortetracycline
  • Cholera Vaccine, Live
  • Demeclocycline
  • Doxycycline
  • Lymecycline
  • Meclocycline
  • Methacycline
  • Methotrexate
  • Minocycline
  • Oxytetracycline
  • Rolitetracycline
  • Tetracycline
  • Venlafaxine
  • Warfarin

Using amoxicillin with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Acenocoumarol
  • Khat
  • Probenecid

Interactions with Food/Tobacco/Alcohol

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other Medical Problems

The presence of other medical problems may affect the use of amoxicillin. Make sure you tell your doctor if you have any other medical problems, especially:

  • Allergy to penicillins or cephalosporin antibiotics (e.g., cefaclor, cefadroxil, cephalexin, Ceftin®, or Keflex®) or
  • Mononucleosis (viral infection)—Should not be used in patients with these conditions.
  • Kidney disease, severe—Use with caution. The effects may be increased because of slower removal of the medicine from the body.
  • Phenylketonuria (PKU)—The chewable tablet contains phenylalanine, which can make this condition worse.

Proper Use of amoxicillin

Take amoxicillin only as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered.

You may take amoxicillin with or without food.

For patients using the oral liquid:

  • Shake the bottle well before each use. Measure the dose with a marked measuring spoon, oral syringe, or medicine cup. The average household teaspoon may not hold the right amount of liquid.
  • You may mix the oral liquid with a baby formula, milk, fruit juice, water, ginger ale, or another cold drink. Be sure the child drinks all of the mixture immediately.

Keep using amoxicillin for the full treatment time, even if you feel better after the first few doses. Your infection may not clear up if you stop using the medicine too soon.

Dosing

The dose of amoxicillin will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of amoxicillin. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For oral dosage forms (capsules, powder for suspension, and tablets):
    • For bacterial infections:
      • Adults, teenagers, and children weighing 40 kilograms (kg) or more—250 to 500 milligrams (mg) every 8 hours, or 500 to 875 mg every 12 hours.
      • Children and infants older than 3 months of age weighing less than 40 kg—Dose is based on body weight and must be determined by your doctor. The usual dose is 20 to 40 milligrams (mg) per kilogram (kg) of body weight per day, divided and given every 8 hours, or 25 to 45 mg per kg of body weight per day, divided and given every 12 hours.
      • Infants 3 months of age and younger—Dose is based on body weight and must be determined by your doctor. The usual dose is 30 mg per kg of body weight per day, divided and given every 12 hours.
    • For treatment of gonorrhea:
      • Adults, teenagers, and children weighing 40 kilograms (kg) or more—3-grams (g) taken as a single dose.
      • Children 2 years of age and older weighing less than 40 kg—Dose is based on body weight and must be determined by your doctor. The usual dose is 50 milligrams (mg) per kilogram (kg) of body weight per day, combined with 25 mg per kg of probenecid, taken as a single dose.
      • Children younger than 2 years of age—Use is not recommended.
    • For treatment of H. pylori infection:
      • Adults—
        • Dual therapy: 1000 milligrams (mg) of amoxicillin and 30 mg of lansoprazole, each given three times a day (every 8 hours) for 14 days.
        • Triple therapy: 1000 mg of amoxicillin, 500 mg of clarithromycin, and 30 mg of lansoprazole, all given two times a day (every 12 hours) for 14 days.
      • Children—Use and dose must be determined by your doctor.

Missed Dose

If you miss a dose of amoxicillin, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

You may store the oral liquid in the refrigerator. Throw away any unused medicine after 14 days. Do not freeze.

Amoxicillin - Clinical Pharmacology

Amoxicillin is stable in the presence of gastric acid and is rapidly absorbed after oral administration. The effect of food on the absorption of Amoxicillin from the tablets and suspension of Amoxicillin has been partially investigated. The 400 mg and 875 mg formulations have been studied only when administered at the start of a light meal. However, food effect studies have not been performed with the 200 mg and 500 mg formulations. Amoxicillin diffuses readily into most body tissues and fluids, with the exception of brain and spinal fluid, except when meninges are inflamed. The half-life of Amoxicillin is 61.3 minutes. Most of the Amoxicillin is excreted unchanged in the urine; its excretion can be delayed by concurrent administration of probenecid. In blood serum, Amoxicillin is approximately 20% protein-bound.

Orally administered doses of 250 mg and 500 mg Amoxicillin capsules result in average peak blood levels 1 to 2 hours after administration in the range of 3.5 mcg/mL to 5 mcg/mL and 5.5 mcg/mL to 7.5 mcg/mL, respectively.

Mean Amoxicillin pharmacokinetic parameters from an open, two-part, single-dose crossover bioequivalence study in 27 adults comparing 875 mg of Amoxicillin with 875 mg of Amoxicillin/clavulanate potassium showed that the 875 mg tablet of Amoxicillin produces an AUC0-∞ of 35.4 ± 8.1 mcg•hr/mL and a Cmax of 13.8 ± 4.1 mcg/mL. Dosing was at the start of a light meal following an overnight fast.

Orally administered doses of Amoxicillin suspension, 125 mg/5 mL and 250 mg/5 mL, result in average peak blood levels 1 to 2 hours after administration in the range of 1.5 mcg/mL to 3 mcg/mL and 3.5 mcg/mL to 5 mcg/mL, respectively.

Oral administration of single doses of 400 mg chewable tablets and 400 mg/5 mL suspension of Amoxicillin to 24 adult volunteers yielded comparable pharmacokinetic data:

* Administered at the start of a light meal.
† Mean values of 24 normal volunteers. Peak concentrations occurred
   approximately 1 hour after the dose.

Dose*

AUC0-∞
   (mcg•hr/mL)

Cmax
   (mcg/mL)†

   Amoxicillin

Amoxicillin
(±S.D.)

Amoxicillin
(±S.D.)

   400 mg (5 mL of suspension)    

17.1 (3.1)

5.92 (1.62)

   400 mg (1 chewable tablet)

17.9 (2.4)

5.18 (1.64)

Detectable serum levels are observed up to 8 hours after an orally administered dose of Amoxicillin. Following a 1 gram dose and utilizing a special skin window technique to determine levels of the antibiotic, it was noted that therapeutic levels were found in the interstitial fluid. Approximately 60% of an orally administered dose of Amoxicillin is excreted in the urine within 6 to 8 hours.

Microbiology


Amoxicillin is similar to ampicillin in its bactericidal action against susceptible organisms during the stage of active multiplication. It acts through the inhibition of biosynthesis of cell wall mucopeptide. Amoxicillin has been shown to be active against most strains of the following microorganisms, both in vitro and in clinical infections as described in the INDICATIONS AND USAGE section.

Aerobic Gram-Positive Microorganisms


Enterococcus faecalis
Staphylococcus spp.* (β-lactamase–negative strains only)
Streptococcus pneumoniae
Streptococcus spp. (α- and β-hemolytic strains only)

*Staphylococci which are susceptible to Amoxicillin but resistant to methicillin/oxacillin should be considered as resistant to Amoxicillin.

Aerobic Gram-Negative Microorganisms


Escherichia coli (β-lactamase–negative strains only)
Haemophilus influenzae (β-lactamase–negative strains only)
Neisseria gonorrhoeae (β-lactamase–negative strains only)
Proteus mirabilis (β-lactamase–negative strains only)

Helicobacter


Helicobacter pylori

Susceptibility Tests

Dilution Techniques


Quantitative methods are used to determine antimicrobial minimum inhibitory concentrations (MICs). These MICs provide estimates of the susceptibility of bacteria to antimicrobial compounds. The MICs should be determined using a standardized procedure. Standardized procedures are based on a dilution method1 (broth or agar) or equivalent with standardized inoculum concentrations and standardized concentrations of ampicillin powder. Ampicillin is sometimes used to predict susceptibility of S. pneumoniae to Amoxicillin; however, some intermediate strains have been shown to be susceptible to Amoxicillin. Therefore, S. pneumoniae susceptibility should be tested using Amoxicillin powder. The MIC values should be interpreted according to the following criteria:

For Gram-Positive Aerobes

Enterococcus

MIC (mcg/mL)

Interpretation

≤8

   Susceptible   (S)   

≥16

   Resistant       (R)   


Staphylococcusa

MIC (mcg/mL)

Interpretation

≤0.25

   Susceptible   (S)   

≥0.5

   Resistant       (R)   


Streptococcus (except S. pneumoniae)

MIC (mcg/mL)

Interpretation

≤0.25

   Susceptible    (S)   

0.5 to 4

   Intermediate  (I)   

≥8

   Resistant       (R)   


S. pneumoniaeb  from non-meningitis sources.

(Amoxicillin powder should be used to determine susceptibility.)

MIC (mcg/mL)

Interpretation

≤2

   Susceptible     (S)   

4

   Intermediate   (I)   

≥8

   Resistant        (R)   


NOTE: These interpretive criteria are based on the recommended doses for respiratory tract infections.

For Gram-Negative Aerobes

Enterobacteriaceae

MIC (mcg/mL)

Interpretation

≤8

   Susceptible     (S)   

16

   Intermediate   (I)   

≥32

   Resistant        (R)   


H. influenzaec

MIC (mcg/mL)

Interpretation

≤1

   Susceptible    (S)   

2

   Intermediate  (I)   

≥4

   Resistant       (R)   


a. Staphylococci which are susceptible to Amoxicillin but resistant to methicillin/oxacillin should be considered as resistant to Amoxicillin.
b. These interpretive standards are applicable only to broth microdilution susceptibility tests using cation-adjusted Mueller-Hinton broth with 2 to 5% lysed horse blood.
c. These interpretive standards are applicable only to broth microdilution test with H. influenzae using Haemophilus Test Medium (HTM).1

A report of “Susceptible” indicates that the pathogen is likely to be inhibited if the antimicrobial compound in the blood reaches the concentrations usually achievable. A report of “Intermediate” indicates that the result should be considered equivocal, and, if the microorganism is not fully susceptible to alternative, clinically feasible drugs, the test should be repeated. This category implies possible clinical applicability in body sites where the drug is physiologically concentrated or in situations where high dosage of drug can be used. This category also provides a buffer zone, which prevents small uncontrolled technical factors from causing major discrepancies in interpretation. A report of “Resistant” indicates that the pathogen is not likely to be inhibited if the antimicrobial compound in the blood reaches the concentrations usually achievable; other therapy should be selected.

Standardized susceptibility test procedures require the use of laboratory control microorganisms to control the technical aspects of the laboratory procedures. Standard ampicillin powder should provide the following MIC values:

Microorganism

MIC Range (mcg/mL)

   E. coli                        ATCC 25922   

2 to 8

   E. faecalis                 ATCC 29212   

0.5 to 2

   H. influenzae            ATCC 49247d   

2 to 8

   S. aureus                   ATCC 29213   

0.25 to 1


Using Amoxicillin to determine susceptibility:

Microorganism

MIC Range (mcg/mL)

   S. pneumoniae         ATCC 49619e   

0.03 to 0.12


d.  This quality control range is applicable to only H. influenzae ATCC 49247 tested by a broth microdilution procedure using HTM.1
e.  This quality control range is applicable to only S. pneumoniae ATCC 49619 tested by the broth microdilution procedure using cation-adjusted Mueller-Hinton broth with 2 to 5% lysed horse blood.

Diffusion Techniques


Quantitative methods that require measurement of zone diameters also provide reproducible estimates of the susceptibility of bacteria to antimicrobial compounds. One such standardized procedure2 requires the use of standardized inoculum concentrations. This procedure uses paper disks impregnated with 10 mcg ampicillin to test the susceptibility of microorganisms, except S. pneumoniae, to Amoxicillin. Interpretation involves correlation of the diameter obtained in the disk test with the MIC for ampicillin.

Reports from the laboratory providing results of the standard single-disk susceptibility test with a 10 mcg ampicillin disk should be interpreted according to the following criteria:

For Gram-Positive Aerobes

Enterococcus

Zone Diameter (mm)

Interpretation

≥17

   Susceptible   (S)   

≤16

   Resistant       (R)   


Staphylococcusf

Zone Diameter (mm)

Interpretation

≥29

   Susceptible   (S)   

≤28

   Resistant       (R)   


β-hemolytic streptococci

Zone Diameter (mm)

Interpretation

≥26

Susceptible  (S)

19 to 25

Intermediate   (I)   

≤18

   Resistant     (R)   


NOTE: For streptococci (other than β-hemolytic streptococci and S. pneumoniae), an ampicillin MIC should be determined.

S. pneumoniae

S. pneumoniaeshould be tested using a 1 mcg oxacillin disk. Isolates with oxacillin zone sizes of ≥20 mm are susceptible to Amoxicillin. An Amoxicillin MIC should be determined on isolates of S. pneumoniae with oxacillin zone sizes of ≤19 mm.

For Gram-Negative Aerobes

Enterobacteriaceae

Zone Diameter (mm)

Interpretation

≥17

   Susceptible     (S)   

14 to 16

   Intermediate   (I)   

≤13

   Resistant        (R)   


H. influenzaeg

Zone Diameter (mm)

Interpretation

≥22

   Susceptible      (S)   

19 to 21

   Intermediate    (I)   

≤18

   Resistant         (R)   


f. Staphylococci which are susceptible to Amoxicillin but resistant to methicillin/oxacillin should be considered as resistant to Amoxicillin.
g. These interpretive standards are applicable only to disk diffusion susceptibility tests with H. influenzae using Haemophilus Test Medium (HTM).2

Interpretation should be as stated above for results using dilution techniques.

As with standard dilution techniques, disk diffusion susceptibility test procedures require the use of laboratory control microorganisms. The 10 mcg ampicillin disk should provide the following zone diameters in these laboratory test quality control strains:

Microorganism

Zone Diameter (mm)

   E. coli                       ATCC 25922   

16 to 22

   H. influenzae            ATCC 49247h   

13 to 21

   S. aureus                   ATCC 25923   

27 to 35


Using 1 mcg oxacillin disk:

Microorganism

Zone Diameter (mm)

   S. pneumoniae          ATCC 49619i   

8 to 12


h. This quality control range is applicable to only H. influenzae ATCC 49247 tested by a disk diffusion procedure using HTM.2
i.  This quality control range is applicable to only S. pneumoniae ATCC 49619 tested by a disk diffusion procedure using Mueller-Hinton agar supplemented with 5% sheep blood and incubated in 5% CO2.

Susceptibility Testing for Helicobacter pylori


In vitro susceptibility testing methods and diagnostic products currently available for determining minimum inhibitory concentrations (MICs) and zone sizes have not been standardized, validated, or approved for testing H. pylori microorganisms.

Culture and susceptibility testing should be obtained in patients who fail triple therapy. If clarithromycin resistance is found, a non-clarithromycin-containing regimen should be used.

Indications and Usage for Amoxicillin


Amoxicillin is indicated in the treatment of infections due to susceptible (ONLY β-lactamase–negative) strains of the designated microorganisms in the conditions listed below:

Infections of the ear, nose, and throat – due to Streptococcus spp. (α- and β-hemolytic strains only), S. pneumoniae, Staphylococcus spp., or H. influenzae.

Infections of the genitourinary tract – due to E. coli, P. mirabilis, or E. faecalis.

Infections of the skin and skin structure – due to Streptococcus spp. (α- and β-hemolytic strains only), Staphylococcus spp., or E. coli.

Infections of the lower respiratory tract – due to Streptococcus spp. (α- and β-hemolytic strains only), S. pneumoniae, Staphylococcus spp., or H. influenzae.

Gonorrhea, acute uncomplicated (ano-genital and urethral infections) – due to N. gonorrhoeae (males and females).

H. pylori eradication to reduce the risk of duodenal ulcer recurrence

Triple Therapy

Amoxicillin/clarithromycin/lansoprazole


Amoxicillin, in combination with clarithromycin plus lansoprazole as triple therapy, is indicated for the treatment of patients with H. pylori infection and duodenal ulcer disease (active or 1-year history of a duodenal ulcer) to eradicate H. pylori. Eradication of H. pylori has been shown to reduce the risk of duodenal ulcer recurrence. (See CLINICAL STUDIES and DOSAGE AND ADMINISTRATION.)

Dual Therapy

Amoxicillin/lansoprazole


Amoxicillin, in combination with lansoprazole delayed-release capsules as dual therapy, is indicated for the treatment of patients with H. pylori infection and duodenal ulcer disease (active or 1-year history of a duodenal ulcer) who are either allergic or intolerant to clarithromycin or in whom resistance to clarithromycin is known or suspected. (See the clarithromycin package insert, MICROBIOLOGY.) Eradication of H. pylori has been shown to reduce the risk of duodenal ulcer recurrence. (See CLINICAL STUDIES and DOSAGE AND ADMINISTRATION.)

To reduce the development of drug-resistant bacteria and maintain the effectiveness of Amoxicillin and other antibacterial drugs, Amoxicillin should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy.

Indicated surgical procedures should be performed.

Index Terms

  • p-Hydroxyampicillin
  • Amoxicillin Trihydrate
  • Amoxil
  • Amoxycillin

Brand Names U.S.

  • Moxatag

Pharmacology

Inhibits bacterial cell wall synthesis by binding to one or more of the penicillin-binding proteins (PBPs) which in turn inhibits the final transpeptidation step of peptidoglycan synthesis in bacterial cell walls, thus inhibiting cell wall biosynthesis. Bacteria eventually lyse due to ongoing activity of cell wall autolytic enzymes (autolysins and murein hydrolases) while cell wall assembly is arrested.

Absorption

Oral: Immediate-release: Rapid with or without food

Extended-release: Rate of absorption is slower compared to immediate-release formulations; food decreases the rate but not extent of absorption

Distribution

Readily into liver, lungs, prostate, muscle, middle ear effusions, maxillary sinus secretions, bone, gallbladder, bile, and into ascitic and synovial fluids; poor CSF penetration (except when meninges are inflamed)

Excretion

Urine (60% as unchanged drug); lower in neonates

Time to Peak

Capsule; oral suspension: 1 to 2 hours; Chewable tablet: 1 hour; Extended-release tablet: 3.1 hours

Half-Life Elimination

Adults: Immediate-release: 61.3 minutes; Extended-release: 90 minutes

Protein Binding

~20%

Use Labeled Indications

Ear, nose, and throat infections (pharyngitis/tonsillitis, otitis media, rhinosinusitis): Immediate-release: Treatment of infections due to beta-lactamase-negative Streptococcus spp (alpha- and beta-hemolytic isolates only), Streptococcus pneumoniae, Staphylococcus spp., or Haemophilus influenzae.

Genitourinary tract infections: Immediate-release: Treatment of infections of the genitourinary tract due to beta-lactamase-negative Escherichia coli, Proteus mirabilis, or Enterococcus faecalis.

Helicobacter pylorieradication: Immediate-release: Eradication of H. pylori to reduce the risk of duodenal ulcer recurrence as a component of combination therapy in patients with active or 1 year history of duodenal ulcer disease.

Lower respiratory tract infections (including pneumonia): Immediate-release: Treatment of infections of the lower respiratory tract due to beta-lactamase-negative Streptococcus spp. (alpha- and beta-hemolytic strains only), Streptococcus pneumoniae, Staphylococcus spp., or H. influenzae.

Pharyngitis and tonsillitis: Extended-release: Treatment of tonsillitis and/or pharyngitis due to Streptococcus pyogenes in adults and pediatric patients ≥12 years.

Skin and skin structure infections: Immediate-release: Treatment of infections of the skin and skin structure due to beta-lactamase-negative Streptococcus spp. (alpha- and beta-hemolytic strains only), Staphylococcus spp., or E. coli.

Contraindications

Serious hypersensitivity to amoxicillin (eg, anaphylaxis, Stevens-Johnson syndrome) or to other beta-lactams, or any component of the formulation

Administration

Oral: Administer around-the-clock to promote less variation in peak and trough serum levels.

Extended release: Administer within 1 hour of finishing a meal; do not chew or crush tablet.

Suspension: Shake well before use; may be mixed with formula, milk, fruit juice, water, ginger ale, or cold drinks; administer dose immediately after mixing.

What happens if i miss a dose (moxatag)?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

Usual Adult Dose for Helicobacter pylori Infection

Immediate-release:
-Dual Therapy: 1 g orally every 8 hours for 14 days in combination with lansoprazole
-Triple Therapy: 1 g orally every 12 hours for 14 days in combination with clarithromycin and lansoprazole

Comments: Refer to clarithromycin and lansoprazole for full prescribing information.

Usual Adult Dose for Lyme Disease - Carditis

Infectious Diseases Society of America (IDSA) recommendations: 500 mg orally 3 times a day for 14 to 28 days

Comments:
-Duration of treatment depends upon severity of condition being treated.
-Current guidelines should be consulted for additional information.

Usual Pediatric Dose for Sinusitis

Immediate-Release Formulations:
Mild, Moderate, or Severe Infection:
3 months or younger: Up to 30 mg/kg/day orally in divided doses every 12 hours

Comments:
-Treatment should be continued for a minimum of 48 to 72 hours beyond the time the patient becomes asymptomatic or evidence of bacterial eradication occurs.
-At least 10 days of treatment for any infection caused by Streptococcus pyogenes is recommended to prevent the occurrence of acute rheumatic fever.

Immediate-Release Formulations:
Mild to Moderate Infection:
4 months or older:
-Less than 40 kg: 20 mg/kg/day orally in divided doses every 8 hours or 25 mg/kg/day in divided doses every 12 hours
-At least 40 kg: 250 mg orally every 8 hours or 500 mg every 12 hours

Severe Infection:
4 months or older:
-Less than 40 kg: 40 mg/kg/day orally in divided doses every 8 hours or 45 mg/kg/day in divided doses every 12 hours
-At least 40 kg: 500 mg orally every 8 hours or 875 mg every 12 hours

Comments: Dosing for infections caused by bacteria that are intermediate in their susceptibility should follow recommendations for severe infections.

Uses: For the treatment of infections of the ear, nose and throat due to susceptible (only beta lactamase negative) isolates of Streptococcus species (alpha and beta-hemolytic isolates only) Streptococcus pneumoniae, Staphylococcus species, or Haemophilus influenzae; for the treatment of infections of the genitourinary tract due to susceptible (only beta lactamase negative) isolates of Escherichia coli, Proteus mirabilis, or Enterococcus faecalis; and for the treatment of infections of the skin and structure due to susceptible (only beta lactamase negative) isolates of Streptococcus species (alpha and beta-hemolytic isolates only) S pneumoniae, Staphylococcus species, and H influenzae

Usual Pediatric Dose for Urinary Tract Infection

Immediate-Release Formulations:
Mild, Moderate, or Severe Infection:
3 months or younger: Up to 30 mg/kg/day orally in divided doses every 12 hours

Comments:
-Treatment should be continued for a minimum of 48 to 72 hours beyond the time the patient becomes asymptomatic or evidence of bacterial eradication occurs.
-At least 10 days of treatment for any infection caused by Streptococcus pyogenes is recommended to prevent the occurrence of acute rheumatic fever.

Immediate-Release Formulations:
Mild to Moderate Infection:
4 months or older:
-Less than 40 kg: 20 mg/kg/day orally in divided doses every 8 hours or 25 mg/kg/day in divided doses every 12 hours
-At least 40 kg: 250 mg orally every 8 hours or 500 mg every 12 hours

Severe Infection:
4 months or older:
-Less than 40 kg: 40 mg/kg/day orally in divided doses every 8 hours or 45 mg/kg/day in divided doses every 12 hours
-At least 40 kg: 500 mg orally every 8 hours or 875 mg every 12 hours

Comments: Dosing for infections caused by bacteria that are intermediate in their susceptibility should follow recommendations for severe infections.

Uses: For the treatment of infections of the ear, nose and throat due to susceptible (only beta lactamase negative) isolates of Streptococcus species (alpha and beta-hemolytic isolates only) Streptococcus pneumoniae, Staphylococcus species, or Haemophilus influenzae; for the treatment of infections of the genitourinary tract due to susceptible (only beta lactamase negative) isolates of Escherichia coli, Proteus mirabilis, or Enterococcus faecalis; and for the treatment of infections of the skin and structure due to susceptible (only beta lactamase negative) isolates of Streptococcus species (alpha and beta-hemolytic isolates only) S pneumoniae, Staphylococcus species, and H influenzae

Usual Pediatric Dose for Tonsillitis/Pharyngitis

12 years or older:
-Extended-release: 775 mg orally once a day within 1 hour after a meal for 10 days

Comments: The full 10-day course of treatment should be completed in order to be effective.

Uses: For the treatment of tonsillitis and/or pharyngitis secondary to S pyogenes

IDSA recommendations:
Immediate-release: 50 mg/kg (maximum 1000 mg) orally once a day or 25 mg/kg (maximum 500 mg) twice a day

Use: For the treatment of Group A Streptococcal pharyngitis

Liver Dose Adjustments

Data not available

Response and Effectiveness

  • Amoxicillin is rapidly absorbed after oral administration and peak levels are reached 1-2 hours after dosing. However, it may take up to 24-72 hours of regular dosing before infection symptoms start to abate.
  • Amoxicillin is effectively distributed throughout most body tissues and fluids. The exception is the brain and spinal cord, where it only penetrates if the meninges (the membranes that enclose the brain and spinal cord) are inflamed.

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What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include confusion, behavior changes, a severe skin rash, urinating less than usual, or seizure (black-out or convulsions).

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