Penicillins

The penicillins are the oldest class of antibiotics. Penicillins have a common chemical structure which they share with the cephalosporins. Penicillins are generally bactericidal, inhibiting formation of the cell wall. Penicillins are used to treat skin infections, dental infections, ear infections, respiratory tract infections, urinary tract infections, gonorrhea.

There are four types of penicillins:

·         The natural penicillins are based on the original penicillin-G structure. Penicillin-G types are effective against gram-positive strains of streptococci, staphylococci, and some gram-negative bacteria such as meningococcus.

·         Penicillinase-resistant penicillins, notably methicillin and oxacillin, are active even in the presence of the bacterial enzyme that inactivates most natural penicillins.

·         Aminopenicillins such as ampicillin and amoxicillin have an extended spectrum of action compared with the natural penicillins. Extended spectrum penicillins are effective against a wider range of bacteria.

Penicillins side effects

Penicillins are among the least toxic drugs known. The most common side effect of penicillin is diarrhea. Nausea, vomiting, and upset stomach are also common. In rare cases penicillins can cause immediate and delayed allergic reactions - specifically, skin rashes, fever, and anaphylactic shock. Penicillins are classed as category B during pregnancy.