n. an antibiotic that was derived from the mould Penicillium rubrum and first became available for treating bacterial infections in 1941. Since then, a number of naturally occurring penicillins have been developed to treat a wide variety of infections, notably benzylpenicillin (penicillin G), administered by injection, and phenoxymethylpenicillin (penicillin V), which is administered orally. There are few serious side-effects, but some patients are allergic to penicillin and develop such reactions as skin rashes and potentially fatal anaphylaxis. Many antibiotics are derived from the penicillins, including amoxicillin, ampicillin, and ticarcillin; these are known as semisynthetic penicillins. All penicillins except flucloxacillin are beta-lactam antibiotics and are sensitive to penicillinase.
Subjects: Science and Mathematics — Medicine and Health.