Amoxicillin

Amoxicillin is a prescription antibiotic which is used to treat a wide variety of bacterial infections. This medication is a penicillin-type antibiotic. It works by stopping the growth of bacteria.

• Amoxicillin treats only bacterial infections. It will not work for viral infections (such as common cold, flu). Unnecessary use or misuse of any antibiotic can lead to its decreased effectiveness.
• Amoxicillin is also used with other medications to treat stomach/intestinal ulcers caused by the bacteria H. pylori and to prevent the ulcers from returning.
• Amoxicillin is available under the following different brand names: Amoxil, Moxatag, and Trimox.

Dosages of Amoxicillin

Adult and pediatric dosages

Oral Solution

• 50 mg/5mL
• 125 mg/5mL
• 200 mg/5mL
• 250 mg/5mL
• 400 mg/5mL

Capsule

• 250 mg
• 500 mg
• Tablet
• 500 mg
• 875 mg

Chewable Tablet

• 125 mg
• 250 mg

Extended-release (Moxatag)

• 775 mg

Dosage Considerations – Should be Given as Follows:

Adult Dosage Considerations

• Ear, Nose, and Throat Infections

Mild to moderate infections

• 500 mg orally every 12 hours or 250 mg orally every 8 hours for 10-14 days

Severe infections

• 875 mg orally every 12 hours or 500 mg orally every 8 hours for 10-14 days

Tonsillitis/pharyngitis

• Moxatag: 775 mg orally once per day for 10 days, taken within 1 hour after finishing a meal

Genitourinary Tract Infections

Mild to moderate infections

• 500 mg orally every 12 hours or 250 mg orally every 8 hours

Severe infections

• 875 mg orally every 12 hours or 500 mg orally every 8 hours

Spectrum of action

• E coli, P mirabilis, or E faecalis

Skin and Skin Structure Infections

Mild to moderate infections

• 500 mg orally every 12 hours or 250 mg orally every 8 hours

Severe infections

• 875 mg orally every 12 hours or 500 mg orally every 8 hours

Tonsillitis

• 775 mg (ER tablets) orally once per day for 10 days

Lower Respiratory Tract Infections

• 875 mg orally every 12 hours or 500 mg orally every 8 hours for 10-14 days

Helicobacter Pylori

H pylori infection and active or 1-year history of duodenal ulcer

Triple therapy

• 1 g orally every 12 hours for 14 days with lansoprazole (30 mg) and clarithromycin (500 mg)

Dual therapy

• 1 g orally every 8 hours for 14 days with lansoprazole (30 mg) in patients intolerant of, or resistant to, clarithromycin
• Anthrax

Post-exposure inhalational prophylaxis

• 500 mg orally every 8 hours

Infective Endocarditis

Prophylaxis

• 2 g orally 30-60 min before procedure

Dosing considerations

AHA guidelines recommend prophylaxis only in high-risk patients undergoing invasive procedures who have a history of cardiac conditions that predispose them to a risk of infection

Lyme Disease (Off-label)

Chronic migrating rash and other symptoms of early dissemination

• 500 mg orally every 8 hours (depending on the size of patient) for 3-4 weeks
• 50 mg/kg/day every 8 hours in divided doses; maximum 500 mg/dose

Chlamydial Infection in Pregnant Women (Off-label)

• First trimester: 500 mg orally every 8 hours for 7 days

Dosing considerations

• First trimester: Test to document chlamydial eradication and retest for infection 3 months after treatment
• Second or third trimester: Test to document chlamydial eradication

Limitation of Use

• For use when susceptibility test results show susceptibility to amoxicillin, indicating no beta-lactamase production

Administration

• Take without regard to meals

Dosing Modifications

• Renal impairment: Patients with impaired renal function do not generally require dose reduction unless the impairment is severe; do not administer extended-release product in patients with creatinine clearance under 30 mL/min
• GFR under 30 mL/min: Should not receive 875 mg (immediate release) or 775 mg (extended release)
• GFR 10-30 mL/min: 250-500 mg every 12 hours, depending on the severity of infection
• GFR under 10 mL/min: 250-500 mg every 24 hours depending on the severity of infection
• Hemodialysis patients: 250-500 mg every 24 hours, depending on the severity of infection; patients should receive an additional dose during and at the completion of dialysis; do not administer the extended-release product or 875 mg immediate release.

Pediatric Dosages Considerations:

Ear, Nose, and Throat Infections

Mild to moderate infections

• Under 3 months: 30 mg/kg/day orally divided every 12 hours for 48-72 hours; for less than 10 days for S pyogenes infections
• Older than 3 months and under 40 kg: 25 mg/kg/day orally divided every 12 hours or 20 mg/kg/day orally divided every 8 hours
• Over 40 kg: 500 mg orally every 12 hours or 250 mg orally every 8 hours for 10-14 days

Severe infections

• Under 3 months: 30 mg/kg/day orally divided every 12 hours for 48-72 hours; for less than 10 days for S pyogenes infections
• Older than 3 months and less than 40 kg: 45 mg/kg/day orally divided every 12 hours or 40 mg/kg/day orally divided every 8 hours
• Over 40 kg: 875 mg orally every12 hour or 500 mg orally every 8 hours for 10-14 days

Tonsillitis/Streptococcal pharyngitis

• 50 mg/kg orally every day for 10 days, not to exceed 1 g/day, orally 25 mg/kg orally twice daily for 10 days, not to exceed 500 mg/dose
• Older than 12 years: 775 mg (Moxatag) orally once per day for 10 days, taken within 1 hour after a meal (swallow tablet whole; do not crush or chew)

Acute Otitis Media

• Older than 3 months and under 40kg: 80-90 mg/kg/day orally divided every 8-12 hours
• Over 40 kg: 500 mg orally every 12 hours or 250 mg orally every 8 hours for 10-14 days

Lower Respiratory Tract Infections

Mild, moderate, or severe infections

• Under 3 months: greater than or equal to 30 mg/kg/day orally divided every 12 hours for 48-72 hours; for less than 10 days for S pyogenes infections
• Older than 3 months and under 40 kg: 45 mg/kg/day orally divided every 12hr or 40 mg/kg/day orally divided every 8 hours
• Over 40kg: 875 mg orally every 12 hours or 500 mg orally every 8 hours for 10-14 days

Pneumonia, community-acquired (Off-label)

Since M. pneumoniae is the primary pathogen that causes pneumonia in patients 5-15 years old, a macrolide antibiotic may be the first-choice treatment.

• Under 3 months: Safety and efficacy not established
• Older than 3 months:

Immediate release

• Empiric treatment: 90 mg/kg/day orally divided every 12 hours for 10 days; not to exceed 4,000 mg/day
• Group A Streptococcus: 50-75 mg/kg/day orally divided every 12 hours for 10 days; not to exceed 4,000 mg/day
• H. influenza: 75-100 mg/kg/day orally divided every 8 hours for 10 days; not to exceed 4,000 mg/day
• S. pneumonia (mild infection or step-down therapy or when MICs to penicillin equal to or greater than 2.0 mcg/mL): 90 mg/kg/day orally divided every 12 hours or 45 mg/kg/day divided every 8 hours for 10 days; not to exceed 4,000 mg/day

Anthrax (Off-label)

Post-exposure inhalational prophylaxis

• Under 40 kg: 15 mg/kg orally every 8 hours (minimum recommended dose; should not be greater than 45 mg/kg/day or given less than every 8 hours
• Over 40 kg: 500 mg orally every 8 hours
• 80 mg/kg/day orally divided every 8 hours for 4 weeks (with simultaneous vaccine) or for 60 days (without vaccine)

Infective Endocarditis (Off-label)

Prophylaxis

• 50 mg/kg orally 30-60 min before procedure

Dosing considerations

AHA guidelines recommend prophylaxis only in high-risk patients undergoing invasive procedures with a history of cardiac conditions that predispose them to infection

Lyme Disease (Off-label)

Chronic migrating rash and other symptoms of early dissemination

• Under 3 months: Safety and efficacy not established
• Over 3 months and 40 kg: 25-50 mg/kg/day divided every 8 hours; not to exceed 500 mg.

Administration

• Take without regard to meals.
• Mixing oral suspension: Tap bottle until all powder flows freely; add approximately one-third of the total amount of water for reconstitution and shake vigorously to wet powder; add remainder of water and shake vigorously again
• After reconstitution, place the required amount of suspension directly on the child's tongue for swallowing; if the taste is unacceptable, the required amount of suspension can be added to the formula, milk, fruit juice, water, ginger ale, or other cold drinks; preparation must be taken immediately.
• Shake the suspension well before using; any unused portion must be discarded after 14 days.

Common side effects of amoxicillin include:

• acute allergic reaction
• anemia
• elevated liver enzymes
• persistent superficial infections of the skin
• diarrhea
• headache
• nausea
• vomiting
• rash
• antibiotic-associated inflammation of the colon
• serum sickness-like reactions

Other (post-marketing) side effects of Amoxicillin reported include:

• persistent superficial infections of the skin
• gastrointestinal
  • black hairy tongue
  • hemorrhagic/pseudomembranous colitis (may occur during or after treatment)

• Hypersensitivity reactions
  • liver dysfunction
  • cholestatic jaundice
  • hepatic cholestasis
  • acute cytolytic hepatitis

• Renal (crystalluria)

• Anemia
  • hemolytic anemia
  • Low platelet count (thrombocytopenia)
  • thrombocytopenic purpura
  • eosinophilia
  • Low white blood cell count (leukopenia)
  • agranulocytosis

• Central nervous system reactions
  • reversible hyperactivity
  • agitation
  • anxiety
  • insomnia
  • confusion
  • convulsions
  • behavioral changes
  • dizziness

• Tooth discoloration (brown, yellow, or gray staining)

This document does not contain all possible side effects and others may occur. Check with your physician for additional information about side effects.

If your doctor has directed you to use this medication for diabetes, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

• Severe Interactions of Amoxicillin include:
  • none
• Amoxicillin has moderate interactions with at least 27 different drugs.
• Mild Interactions of Amoxicillin include:
  • amiloride
  • azithromycin
  • aztreonam
  • chloramphenicol
  • clarithromycin
  • erythromycin base
  • erythromycin ethylsuccinate
  • erythromycin lactobionate
  • erythromycin stearate
  • pyridoxine (antidote)

This document does not contain all possible interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist. Check with your physician if you have health questions or concerns.

Warnings

Documented hypersensitivity to penicillins, cephalosporins, and imipenem.

• This medication contains amoxicillin. Do not take Amoxil, Moxatag, or Trimox, if you are allergic to amoxicillin or any ingredients contained in this drug.
• Keep out of reach of children. In case of overdose, get medical help or contact a Poison Control Center immediately.

Contraindications

• None.

Effects of Drug Abuse

• None.

Short-Term Effects

• See "What Are Side Effects Associated with Using Amoxicillin?"

Long-Term Effects

• See "What Are Side Effects Associated with Using Amoxicillin?"

Cautions

• The severe allergic reaction has been reported rarely but is more likely to occur following parenteral therapy with penicillins.
• Clostridium difficile-associated diarrhea (CDAD) has been reported with the use of nearly all antibacterial agents; severity may range from mild diarrhea to fatal colitis; CDAD may occur over 2 months after discontinuation of therapy; if CDAD is suspected or confirmed, discontinue immediately and begin appropriate fluid and electrolyte management, protein supplementation, antibiotic treatment of C difficile, and surgical evaluation.
• Do not administer in patients with infectious mononucleosis or mono because of the risk of the development of red skin rash.
• Do not administer to patients in the absence of a proven or suspected bacterial infection because of the risk of the development of drug-resistant bacteria.
• Superinfections with bacterial or fungal pathogens may occur during therapy; if suspected, discontinue immediately and begin appropriate treatment.
• Chewable tablets contain aspartame, which contains phenylalanine.
• Use caution in patients with allergies to cephalosporins, carbapenems.
• Endocarditis prophylaxis: use for only high-risk patients, as per recent AHA guidelines.
• High doses may cause false urine glucose tests by some methods

Pregnancy and Lactation

• The use of amoxicillin in pregnancy may be acceptable. Either animal studies show no risk but human studies are not available or animal studies showed minor risks and human studies are done and showed no risk.
• Amoxicillin is excreted in breast milk. Use caution when lactating.