Penicillin G Potassium - Penicillin G Potassium injection, Powder, For Solution

Buffered penicillin G potassium for injection is indicated in the treatment of serious infections caused by susceptible strains of the designated microorganisms in the conditions listed below. Appropriate culture and susceptibility tests should be done before treatment in order to isolate and identify organisms causing infection and to determine their susceptibility to penicillin G. Therapy with Buffered penicillin G potassium for injection may be initiated before results of such tests are known when there is reason to believe the infection may involve any of the organisms listed below, however, once these results become available, appropriate therapy should be continued.

To reduce the development of drug-resistant bacteria and maintain the effectiveness of penicillin G potassium and other antibacterial drugs, penicillin G potassium should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy.

Buffered penicillin G potassium for injection may be given intravenously or intramuscularly. The usual dose recommendations are as follows:

* Because of its short half-life, penicillin G is administered in divided doses, usually every 4 to 6 hours with the exception of meningococcal meningitis/septicemia, i.e., every 2 hours.

The Jarisch-Herxheimer reaction is a systemic reaction, that may occur after the initiation of penicillin therapy in patients with syphilis or other spirochetal infections (i.e., Lyme disease and Relapsing fever). The reaction begins one to two hours after initiation of therapy and disappears within 12 to 24 hours. It is characterized by fever, chills, myalgias, headache, exacerbation of cutaneous lesions, tachycardia, hyperventiliation, vasodilation with flushing and mild hypotension. The pathogenesis of the Herxheimer reaction may be due to the release from the spirochaete of host stable pyrogen.

Bacteriostatic antibacterials (i.e., chloramphenicol, erythromycins, sulfonamides or tetracyclines) may antagonize the bactericidal effect of penicillin, and concurrent use of these drugs should be avoided. This has been documented

Penicillin blood levels may be prolonged by concurrent administration of probenecid which blocks the renal tubular secretion of penicillins.

Other drugs may compete with penicillin G for renal tubular secretion and thus prolong the serum half-life of penicillin. These drugs include: aspirin, phenylbutazone, sulfonamides, indomethacin, thiazide diuretics, furosemide and ethacrynic acid.

Buffered penicillin G potassium for injection, USP is sterile penicillin G potassium powder for reconstitution. It is an antibacterial agent intended for intravenous or intramuscularly use.

Chemically, penicillin G potassium is monopotassium (2S,5R,6R)-3,3-dimethyl-7-oxo-6-(2-phenylacetamido)-4-thia-1-azabicyclo (3.2.0) heptane-2-carboxylate, and has the following chemical structure:

Penicillin G potassium, a water soluble benzylpenicillin, is a white to almost white crystalline powder which is almost odorless and/or after reconstitution a colorless solution. The pH of freshly constituted solutions usually ranges from 6 to 8.5. Sodium citrate and citric acid have been added as a buffer.

Buffered penicillin G potassium for injection, USP is supplied in vials equivalent to 1,000,000 units (1 million units), 5,000,000 units (5 million units), or 20,000,000 units (20 million units) of penicillin G as the potassium salt. Each million unit contains approximately 7.9 milligrams of sodium (0.34 mEq) and 65.6 milligrams of potassium (1.68 mEq).