AMPICILLIN

semisynthetic penicillin, one of the first such antibiotics developed. It is created by attaching acid radicals to the central structure of 6-aminopenicillanic acid. Similar in action to penicillin Gthe most widely used natural penicillinampicillin (or alpha-aminobenzylpenicillin) is more stable in stomach acids and therefore may be given orally; it is also more active against certain strains of bacteria. Because ampicillin is easy to administer, it is a popular penicillin antibiotic. It is used regularly to treat common urinary-tract infections, some respiratory infections, and bacterial meningitis in children, although many strains of Hemophilus influenzae (the most common cause of bacterial meningitis) are now resistant to ampicillin, and it commonly is used along with other drugs. The potential side effects of ampicillin are similar to those of other penicillinsi.e., chiefly allergic reactions ranging from skin rashes and hives to life-threatening anaphylactic shock (very rare). People who are allergic to other drugs in this family are also likely to react to ampicillin. The incidence of skin rashes is higher with ampicillin than with other penicillins, a factor that suggests a possible toxic reaction, as well as a truly allergic response.