Get your patient on Pfizerpen - Penicillin G Potassium powder, For Solution (Penicillin G Potassium)

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 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 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.

This product should not be administered to patients requiring less than one million units per dose (see Precautions-Pediatric Use ).

Penicillin G is relatively nontoxic, and dosage adjustments are generally required only in cases of severe renal impairment. The recommended dosage regimens are as follows:

Creatinine clearance less than 10 mL/min/1.73m ² ; administer a full loading dose (see recommended dosages in the tables above) followed by one-half of the loading dose every 8–10 hours.

Uremic patients with a creatinine clearance greater than 10 mL/min/1.73m ² ; administer a full loading dose (see recommended dosages in the tables above) followed by one-half of the loading dose every 4–5 hours. Additional dosage modification should be made in patients with hepatic disease and renal impairment.

For most acute infections, treatment should be continued for at least 48 to 72 hours after the patient becomes asymptomatic. Antibiotic therapy for Group A β-hemolytic streptococcal infections should be maintained for at least 10 days to reduce the risk of rheumatic fever.

Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration whenever solution and container permit.

The following table shows the amount of solvent required for solution of various concentrations:

When the required volume of solvent is greater than the capacity of the vial, the penicillin can be dissolved by first injecting only a portion of the solvent into the vial, then withdrawing the resultant solution and combining it with the remainder of the solvent in a larger sterile container.

Buffered Pfizerpen (Penicillin G Potassium for Injection, USP) is highly water soluble. It may be dissolved in small amounts of Water for Injection, or Sterile Isotonic Sodium Chloride Solution for Parenteral Use. All solutions should be stored in a refrigerator. When refrigerated, penicillin solutions may be stored for seven days without significant loss of potency.

Buffered Pfizerpen for Injection may be given intramuscularly or by continuous intravenous infusion for dosages of 500,000, 1,000,000, or 5,000,000 units. It is also suitable for intrapleural, intraarticular, and other local instillations.

THE 20,000,000 UNIT DOSAGE MAY BE ADMINISTERED BY INTRAVENOUS INFUSION ONLY.

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 or 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, hyperventilation, vasodilation with flushing and mild hypotension. The pathogenesis of the Herxheimer reaction may be due to the release from the spirochetes of heat-stable pyrogen.

The reported incidence of allergic reactions to all penicillins ranges from 0.7 to 10 percent in different studies (see Warnings ). Sensitization is usually the result of previous treatment with a penicillin, but some individuals have had immediate reactions when first treated. In such cases, it is postulated that prior exposure to penicillin may have occurred via trace amounts present in milk or vaccines.

Two types of allergic reactions to penicillin are noted clinically – immediate and delayed.

Immediate reactions usually occur within 20 minutes of administration and range in severity from urticaria and pruritus to angioneurotic edema, laryngospasm, bronchospasm, hypotension, vascular collapse and death (see Warnings ). Such immediate anaphylactic reactions are very rare and usually occur after parenteral therapy, but a few cases of anaphylaxis have been reported following oral therapy. Another type of immediate reaction, an accelerated reaction, may occur between 20 minutes and 48 hours after administration and may include urticaria, pruritus, fever and, occasionally, laryngeal edema.

Delayed reactions to penicillin therapy usually occur within 1–2 weeks after initiation of therapy. Manifestations include serum sickness-like symptoms, i.e., fever, malaise, urticaria, myalgia, arthralgia, abdominal pain and various skin rashes, ranging from maculopapular eruptions to exfoliative dermatitis.

Contact dermatitis has been observed in individuals who prepare penicillin solutions.

Pseudomembranous colitis has been reported with the onset occurring during or after penicillin G treatment. Nausea, vomiting, stomatitis, black or hairy tongue, and other symptoms of gastrointestinal irritation may occur, especially during oral therapy.

Reactions include neutropenia, which resolves after penicillin therapy is discontinued; Coombs-positive hemolytic anemia, an uncommon reaction, occurs in patients treated with intravenous penicillin G in doses greater than 10 million units/day and who have previously received large doses of the drug; and with large doses of penicillin, a bleeding diathesis can occur secondary to platelet dysfunction.

Penicillin G Potassium for Injection (1 million units contains 1.68 mEq of potassium ion) may cause serious and even fatal electrolyte disturbances, i.e ., hyperkalemia, when given intravenously in large doses.

Neurotoxic reactions including hyperreflexia, myoclonic twitches, seizures and coma have been reported following the administration of massive intravenous doses, and are more likely in patients with impaired renal function.

Renal tubular damage and interstitial nephritis have been associated with large intravenous doses of penicillin G. Manifestations of this reaction may include fever, rash, eosinophilia, proteinuria, eosinophiluria, hematuria and a rise in serum urea nitrogen.

Discontinuation of penicillin G results in resolution in the majority of patients.

Phlebitis and thrombophlebitis may occur, and pain at the injection site has been reported with intravenous administration.

To report SUSPECTED ADVERSE EVENTS, contact ( insert name of manufacturer ) at ( insert manufacturer's phone number ) or FDA at 1-800-FDA-1088 or http://www.fda.gov/ for voluntary reporting of adverse reactions.

Penicillin G exerts a bactericidal action against penicillin-susceptible microorganisms during the stage of active multiplication. It acts through the inhibition of biosynthesis of cell wall peptidoglycan rendering the cell wall osmotically unstable. It is not active against the penicillinase-producing bacteria, which include many strains of staphylococci or against organisms resistant to beta-lactams because of alterations in the penicillin-binding proteins, such as methicillin-resistant staphylococci. Penicillin G is highly active in vitro against streptococci (groups A, B, C, G, H, L and M) and Neisseria meningitidis .

Other organisms susceptible to penicillin G are N. gonorrhoeae , Corynebacterium diphtheriae , Bacillus anthracis , Clostridium spp., Actinomyces species, " Spirillum minus ", Streptobacillus moniliformis, Listeria monocytogenes and Leptospira spp.; Treponema pallidum is extremely sensitive to the bactericidal action of penicillin G.

Some species of gram-negative bacilli were previously considered susceptible to very high intravenous doses of penicillin G (up to 80 million units/day) including some strains of Escherichia coli, Proteus mirabilis, Salmonella spp. and Shigella spp.; Enterobacter aerogenes (formerly Aerobacter aerogenes ) and Alcaligenes faecalis . Penicillin G is no longer considered a drug of choice for infections caused by these organisms.

Store the dry powder below 86°F (30°C).