Phenoxymethylpenicillin, commonly known as penicillin V, is the orally active form of penicillin. It is less active than benzylpenicillin, however, and is appropriate only in conditions where high tissue concentrations are not required. Phenoxymethylpenicillin exerts a bactericidal action against penicillinsensitive microorganisms during the stage of active multiplication.
Procaine benzylpenicillin (rINN), also known as procaine penicillin, is a form of penicillin which is a combination of benzylpenicillin and the local anaesthetic agent procaine. Following deep intramuscular injection, it is slowly absorbed into the circulation and hydrolysed to benzylpenicillin thus it is used where prolonged low concentrations of benzylpenicillin are required.
Ticarcillin is a carboxypenicillin. It is almost invariably sold and used in combination with clavulanate as Timentin. Because it is a penicillin, it also falls within the larger class of beta-lactam antibiotics. Its main clinical use is as an injectable antibiotic for the treatment of gram-negative bacteria, in particular, Pseudomonas aeruginosa.