Amoxicillin belongs to a class of antibiotics called penicillins. Other members of this class include

• ampicillin (Unasyn),
• piperacillin (Pipracil),
• ticarcillin (Ticar), and
• several others.

These antibiotics all have a similar mechanism of action. They do not directly kill bacteria, but they stop bacteria from multiplying by preventing bacteria from forming the walls that surround them. The walls are necessary to protect bacteria from their environment and to keep the contents of the bacterial cell together. Bacteria cannot survive without a cell wall. Amoxicillin is effective against many different bacteria including H. influenzae, N. gonorrhoea, E. coli, Pneumococci, Streptococci, and certain strains of Staphylococci.

The FDA approved Amoxicillin in December 1974.

• Amoxicillin is used to treat infections due to bacteria that are susceptible to the effects of amoxicillin.
• Common bacterial infections that amoxicillin is used for include infections of the
  • middle ear,
  • tonsils,
  • throat,
  • larynx (laryngitis),
  • bronchi (bronchitis),
  • Lungs (pneumonia),
  • urinary tract, and
  • skin.
• It also is used to treat gonorrhea.

Side effects due to amoxicillin include:

• diarrhea,
• dizziness,
• heartburn,
• insomnia,
• nausea,
• itching,
• vomiting,
• confusion,
• abdominal pain,
• easy bruising,
• bleeding,
• rash, and
• allergic reactions.

People who are allergic to the cephalosporin class of antibiotics, which are related to the penicillins, for example, cefaclor (Ceclor), cephalexin (Keflex), and cefprozil (Cefzil), may or may not be allergic to penicillins.

Serious but rare reactions include:

• seizures,
• severe allergic reactions (anaphylaxis), and
• low platelet (thrombocytopenia) or red blood cell count.

Amoxicillin can alter the normal bacteria in the colon and encourage overgrowth of some bacteria such as Clostridium difficile which causes inflammation of the colon (pseudomembranous colitis). Patients who develop signs of pseudomembranous colitis after starting amoxicillin (diarrhea, fever, abdominal pain, and possibly shock) should contact their physician immediately.

• For most infections in adults the dose of amoxicillin is 250 mg every 8 hours, 500 mg every 8 hours, 500 mg every 12 hours or 875 mg every 12 hours, depending on the type and severity of infection.
• For the treatment of adults with gonorrhea, the dose is 3 g given as one dose.
• For most infections, children older than 3 months but less than 40 kg are treated with 25 or 45 mg/kg/day in divided doses every 12 hours or 20 or 40 mg/kg/day with one-third of the daily dose given every 8 hours depending on the type and severity of the infection.
• Amoxicillin can be taken with or without food.

Amoxicillin is rarely associated with important drug interactions.

• Penicillins are generally considered safe for use by pregnant women who are not allergic to penicillin.
• Small amounts of amoxicillin may be excreted in breast milk and may cause diarrhea or allergic responses in nursing infants. Amoxicillin is generally considered safe to use while breastfeeding. Amoxicillin is used to treat infections in the newborn.

Preparations

• Capsules: 250 and 500 mg.
• Tablets: 500 and 875 mg.
• Chewable tablets: 125, 200, 250, and 400 mg.
• Powder for suspension: 50 mg/ml ; 125, 200, 250, and 400 mg/5 ml.
• Tablet (Extended release): 775 mg

Storage

• Amoxicillin capsules as well as the 125 and 250 mg dry powders should b e stored at or below 20 C (68 F).
• Chewable tablets as well as 200 and 400 mg dry powders should be stored at or below 25 C(77 F).
• Trimox capsules and unreconstituted powder should be stored at or below 20 C (68 F), and chewable tablets should be stored at room temperature 15 C to 30 C (59 F to 86 F).
• Powder that has been mixed with water should be discarded after 14 days. Refrigeration is preferred but not required for powder mixed with water.

Other information about amoxicillin

• Amoxicillin is available in generic form and is available by prescription only.
• Brand names available in the US for amoxicillin are Amoxil, Moxatag, and Larotid.