Amoxicillin : Precautions, Contraindications, pregnancy, lactation

Amoxicillin : Precautions, Contraindications, pregnancy, lactation
Amoxicillin shares the toxic potentials of the penicillins, including the risk of hypersensitivity reactions, and the usual precautions of penicillin therapy should be observed. Prior to initiation of therapy with amoxicillin, careful inquiry should be made concerning previous hypersensitivity reactions to penicillins, cephalosporins, or other allergens. There is clinical and laboratory evidence of partial cross-allergenicity among penicillins and other -lactam antibiotics including cephalosporins and cephamycins. Amoxicillin is contraindicated in patients who are hypersensitive to any penicillin.

Because a high percentage of patients with infectious mononucleosis have developed rash during therapy with aminopenicillins, amoxicillin probably should not be used in patients with the disease.

Individuals with phenylketonuria (i.e., homozygous genetic deficiency of phenylalanine hydroxylase) and other individuals who must restrict their intake of phenylalanine should be warned that the amoxicillin 200- and 400-mg chewable tablets contain aspartame which is metabolized in the GI tract to provide 1.82 or 3.64 mg of phenylalanine, respectively, following oral administration. Amoxicillin powder for oral suspension does not contain aspartame.

Renal, hepatic, and hematologic systems should be evaluated periodically during prolonged therapy with amoxicillin.

Pregnancy
Safe use of amoxicillin during pregnancy has not been definitely established. There are no adequate or controlled studies using aminopenicillins in pregnant women, and amoxicillin should be used during pregnancy only when clearly needed. However, amoxicillin has been administered to pregnant women without evidence of adverse effects to the fetus. In addition, use of the drug is currently included in the US Centers For Disease Control and Prevention (CDC) recommendations for the treatment of chlamydial infections during pregnancy and CDC recommendations for the treatment of cutaneous anthrax or for postexposure prophylaxis following exposure to Bacillus anthracis spores.

Lactation
Because amoxicillin is distributed into milk and may lead to sensitization of infants, the drug should be used with caution in nursing women. Because of its general safety in infants, the CDC states that amoxicillin is an option for anti-infective prophylaxis in breast-feeding women when B. anthracis is known to be penicillin susceptible and there is no contraindication to maternal amoxicillin use.