Amoxicillin/clavulanic acid, also abbreviated amox/clav, is a combination drug product used to treat various infections. It is marketed in the US under the trade names Augmentin, Augmentin ES and Augmentin XR.
Amox/clav combines the penicillin derivative amoxicillin with clavulanic acid, an ingredient designed to combat bacterial resistance to penicillin and its relatives. Amox/clav is active against common skin and soft tissue, respiratory and uncomplicated urinary tract pathogens.
Mechanism of Action
Amoxicillin works by inhibiting the production of cell walls in susceptible bacterial strains. However, as some bacterial species evolved, they began to produce beta lactamase, an enzyme that disrupts the chemical structure of penicillin and its relatives, making them ineffective. The addition of clavulanic acid allows amoxicillin to regain its action over these bacteria.
Amox/clav is known to cause diarrhea in up to thirty percent of patients. Nausea and vomiting are also common with amox/clav, but may be reduced by taking the medication with food or milk. Women taking amox/clav may experience vaginal irritation or secondary yeast infection.
Allergic reaction is possible, and may include itching, breathing or swallowing difficulty, rash or swelling. An inflammatory response characterized by lesions of the skin and mucus membranes may also occur. This rare but serious reaction is called Stevens-Johnson syndrome and requires immediate medical attention. Patients experiencing any of these symptoms should seek urgent medical care. A generalized bumpy rash is common with amox/clav use and is not necessarily a sign of allergy. Any skin changes, however, should be reported to a physician. Patients with sensitivity to penicillin or other penicillin relative, amoxicillin or clavulanic acid should not take amox/clav. Patients with sensitivity to cephalosporin antibiotics such as cephalexin may wish to avoid amox/clav due to potential cross-sensitivity.
Major Drug Interactions
Probenecid, an agent used in the treatment of gout may increase amox/clav levels in the blood. The effectiveness of oral contraceptives may be decreased by amox/clav. Women who take oral contraceptives may wish to employ a back up method of birth control during the cycle surrounding treatment. Amox/clav may also increase the blood thinning effects of warfarin. Warfarin doses may require adjustment during amox/clav therapy.
Amox/clav is available in 125mg, 250mg, 400mg, 500mg, 600mg and 875mg doses. Tablets, extended-release tablets, chewable tablets and powder for oral suspension are available. Pediatric doses are typically based on child weight, whereas adult doses depend on type of infection and patient kidney function.
Because the clavulanic acid content varies between formulations, doubling a 250mg dose is not equivalent to a 500mg dose.
Oral suspension should be shaken well prior to dosing, stored in the refrigerator and kept for no longer than ten days. Amox/clav tablets may be stored at room temperature. All dosage forms should be stored in their original containers away from children and pets.
Patients should always finish the entire course of any antibiotic therapy unless directed otherwise by their physician.