They are also, therefore, referred to as being penicillinase-resistant. Broad-spectrum antibiotics
This group of antibiotics is called "broad-spectrum" because they are active against a wide range of Gram-negative bacteria such as Escherichia coli and Salmonella typhi, for which penicillin is not suitable. However, resistance in these organisms is now common. Ampicillin
AmoxicillinThere are many ampicillin precursors in existence. These are inactive compounds that are broken down in the gut to release ampicillin. None of these pro-drugs of ampicillin are in current use: 

Pivampicillin (pivaloyloxymethyl ester of ampicillin)
Bacampicillin
Metampicillin (formaldehyde ester of ampicillin)
Talampicillin
Hetacillin (ampicillin conjugated to acetone)Epicillin is an aminopenicillin that has never seen widespread clinical use. Antipseudomonal antibiotics
The Gram-negative species, Pseudomonas aeruginosa, is naturally resistant to many antibiotic classes. There were many efforts in the 1960s and 1970s to develop antibiotics that are active against Pseudomonas species. There are two chemical classes within the group: carboxypenicillins and ureidopenicillins. All are given by injection: none can be given by mouth. Carboxypenicillins
Carbenicillin
Ticarcillin
Temocillin

Ureidopenicillins
Mezlocillin
Piperacillin
Azlocillin

β-lactamase inhibitors
Clavulanic acid
Sulbactam
Tazobactam

Medical usage
The term "penicillin", when used by itself, may refer to either of two chemical compounds, penicillin G or penicillin V.

Penicillin G
Penicillin G is destroyed by stomach acid, so it cannot be taken by mouth, but doses as high as 2.4 g can be given (much higher than penicillin V). It is given by intravenous or intramuscular injection. It can be formulated as an insoluble salt, and there are two such formulations in current use: procaine penicillin and benzathine benzylpenicillin, which are used only in the treatment of syphilis.
Allergies
Diphenhydramine is effective in treatment of allergies. As of 2007, it was the most commonly used antihistamine for acute allergic reactions in the emergency department.By injection it is often used in addition to epinephrine for anaphylaxis, although as of 2007 its use for this purpose had not been properly studied. Its use is only recommended once acute symptoms have improved. Topical formulations of diphenhydramine are available, including creams, lotions, gels, and sprays. These are used to relieve itching and have the advantage of causing fewer systemic effects (e.g., drowsiness) than oral forms. Movement disorders
Diphenhydramine is used to treat akathisia and Parkinsons disease–like extrapyramidal symptoms caused by antipsychotics. It is also used to treat acute dystonia including torticollis and oculogyric crisis caused by first generation antipsychotics. Sleep
Because of its sedative properties, diphenhydramine is widely used in nonprescription sleep aids for insomnia. The drug is an ingredient in several products sold as sleep aids, either alone or in combination with other ingredients such as acetaminophen (paracetamol) in Tylenol PM or ibuprofen in Advil PM. Diphenhydramine can cause minor psychological dependence. Diphenhydramine has also been used as an anxiolytic.Diphenhydramine has also been used off prescription by parents in an attempt to make their children sleep or remain sedated on long-distance flights.