What do the g and v of penicillin mean?

Different types : Penicillin g can be used orally, IV or as an injection. Penicillin v is a different form and is used orally.

Penicillin: The term "penicillin" is often used generically to refer to benzylpenicillin (penicillin g), procaine benzylpenicillin (procaine penicillin), benzathine benzylpenicillin (benzathine penicillin), and phenoxymethylpenicillin (penicillin v). Procaine penicillin and benzathine penicillin have the same antibacterial activity as benzylpenicillin but act for a longer span of time. Phenoxymethylpenicilli.