Penicillin G

A to Z Drug Facts

 Action Inhibits mucopeptide synthesis of bacterial cell wall.

 Indications

Penicillin G: Treatment of infections caused by susceptible microorganisms.

Penicillin G Procaine: Treatment of moderately severe infections caused by penicillin-G-sensitive microorganisms that are sensitive to low and persistent serum levels achieved with this dose form.

Penicillin G Benzathine: Mild to moderate upper respiratory tract infections, venereal diseases, and prophylaxis of rheumatic fever or chorea caused by penicillin-G-sensitive microorganisms that are susceptible to the low and very prolonged serum levels common to this dosage form.

 Contraindications Hypersensitivity to penicillins. Do not treat severe pneumonia, empyema, bacteremia, pericarditis, meningitis, and purulent or septic arthritis with oral penicillin G during acute stage.

 Route/Dosage

Dosage may vary with site of infection and organism being treated.

Penicillin G (Aqueous Potassium or Sodium)

Adults: IV/IM 1 to 24 million U/day in divided doses q 4 to 6 hr. Children: IV/IM 100,000 to 250,000 U/kg/day in divided doses q 4 hr. Infants (Over 7 Days and more than 2000 g): IM/IV 100,000 U/kg/day in divided doses q 6 hr (meningitis: 200,000 U/kg/day in divided doses q 6 hr). Infants (Under 7 Days and more than 2000 g): IM/IV 50,000 U/kg/day in divided doses q 8 hr (meningitis: 150,000 U/kg/day in divided doses q 8 hr). Infants (Under 7 Days and less than 2000 g): IM/IV 50,000 U/kg/day in divided doses q 12 hr (meningitis: 100,000 U/kg/day in divided doses q 12 hr).

Penicillin G Potassium

Adults and Children older than 12 yr: PO 200,000 to 500,000 U q 6 to 8 hr. Infants and Children younger than 12 yr: PO 25,000 to 90,000 U/kg/day in 3 to 6 divided doses.

Penicillin G Procaine (Aqueous)

Adults and Children (at least 27 kg): IM 600,000 to 1.2 million U/day in 1 to 2 doses. Children (under 27 kg): IM 300,000 U/day.

Congenital Syphilis

Children (under 32 kg): IM 50,000 U/kg/day as a single dose for 10 to 14 days.

Neurosyphillis

Adults: IM 2.4 million U/day plus probenecid 500 mg PO qid, both for 10 to 14 days.

Penicillin G Benzathine

Adults: IM 1.2 to 2.4 million U in 1 dose. Children more than 27 kg: IM 900,000 to 1.2 million U in 1 dose. Children and Infants less than 27 kg: IM 300,000 to 1.2 million U in 1 dose. Newborns: IM 50,000 U/kg in 1 dose.

Penicillin G Benzathine and Procaine Combined

Adults and Children more than 27 kg: IM 2.4 million U in 1 dose. Children 14 to 27 kg: IM 900,000 to 1.2 million U in 1 dose. Children and Infants less than 14 kg: IM 600,000 U in 1 dose.

 Interactions

Anticoagulants (oral and heparin): May increase bleeding risks of anticoagulant by prolonging bleeding time. Beta-blockers: May potentiate anaphylactic reactions of penicillin. Chloramphenicol: May cause synergism or antagonism to develop. Contraceptives, oral: May reduce efficacy of oral contraceptives. Erythromycin: May cause synergism or antagonism to develop. Probenecid: Increases penicillin serum concentration. Tetracyclines: May impair bactericidal effects of penicillin G. Aminoglycosides, parenteral: Penicillin may inactivate aminoglycosides in vitro; do not mix in same IV solution. May be used in combination for synergy if administered separately. Carbohydrate solutions at alkaline pH: Penicillin solutions are rapidly inactivated.

 Lab Test Interferences Antiglobulin (Coombs' test): Drug may cause false-positive results. Urine glucose test: Drug may cause false-positive results with copper sulfate tests (Benedict's test, Fehling's test, or Clinitest tablets); enzyme-based tests (eg, Clinistix, Tes-tape) are not affected. Urine protein determinations: Drug may cause false-positive reactions with sulfosalicylic acid and boiling test, acetic acid test, biuret reaction, and nitric acid test; bromphenol blue test (Multi-Stix) is not affected.

 Adverse Reactions

CNS: Dizziness; fatigue; insomnia; reversible hyperactivity; neurotoxicity (eg, lethargy, neuromuscular irritability, hallucinations, convulsions, seizures). EENT: Itchy eyes; stomatitis; gastritis; sore mouth or tongue; furry tongue; black “hairy” tongue; abnormal taste perception. GI: Glossitis; dry mouth; nausea; anorexia; vomiting; abdominal pain or cramp; epigastric distress; diarrhea or bloody diarrhea; rectal bleeding; flatulence; enterocolitis; pseudomembranous colitis. GU: Interstitial nephritis (eg, oliguria, proteinuria, hematuria, hyaline casts, pyuria); nephropathy; increased BUN and creatinine. HEMATOLOGIC: Decreased hemoglobin, hematocrit, RBC, WBC, neutrophils, lymphocytes, platelets; increased lymphocytes, monocytes, basophils, eosinophils and platelets; abnormal coagulation tests. METABOLIC: Elevated serum alkaline phosphatase, hypernatremia; hypokalemia; hyperkalemia. OTHER: Hypersensitivity reactions (eg, urticaria, angioneurotic edema, laryngospasm, laryngeal edema, bronchospasm, hypotension, vascular collapse, death, maculopapular to exfoliative dermatitis, vesicular eruptions, erythema multiforme, serum sickness, skin rashes); vaginitis; hyperthermia.

 Precautions

Pregnancy: Category B. Lactation: Small amount excreted in breast milk. May cause diarrhea, candidiasis, or allergic response in nursing infant. Electrolyte content: Penicillin G aqueous sodium contains 2 mEq sodium/1 million U. Penicillin G aqueous potassium contains 1.7 mEq potassium and 0.3 mEq sodium/1 million U. Beware of iatrogenic electrolyte abnormalities and fluid overload. Hypersensitivity: Reactions range from mild to life threatening. Administer drug with caution to cephalosporin-sensitive patients because of possible crossreactivity. Procaine sensitivity: If sensitivity to procaine in penicillin G procaine is suspected, inject 0.1 mL of 1% to 2% procaine solution intradermally. If erythema, wheal, flare, or eruption develops, do not use procaine penicillin preparations. Pseudomembranous colitis: May occur because of overgrowth of clostridia. Renal impairment: Use drug with caution; may require dosage adjustment. Superinfection: May result in bacterial or fungal overgrowth of nonsusceptible organisms. Tartrazine sensitivity: Some products contain tartrazine, which may cause allergic-type reactions in susceptible individuals.

 Administration/Storage

• Depending on route of administration, prepare solution using Sterile Water for Injection, Isotonic Sodium Chloride Injection, or Dextrose Injection.
• Administer at regular intervals around clock.
• Give oral form on empty stomach with full glass of water at least 1 hr before or 2 hr after meals.
• Do not administer with acidic juices or carbonated beverages, which may decrease absorption of penicillin G.
• For IM administration, inject deeply into upper outer quadrant of buttock in adults. In infants and small children, inject in midlateral aspect of thigh. With repeated doses, rotate injection sites.
• For IV administration, administer continuously or intermittently. For intermittent infusion, infuse each dose over 1 to 2 hr (adults) or 15 to 30 min (newborns and children).
• Solutions prepared for IV infusion are stable at room temperature for at least 24 hr.
• Dry powder is stable and does not require refrigeration.
• Sterile solutions may be kept in refrigerator for 1 wk.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies.
• Assess patient for infection at beginning and throughout therapy (eg, fever, WBC, appearance of wound).
• Obtain specimens for culture and sensitivity before beginning therapy.
• Have emergency medication (eg, epinephrine, antihistamine) and equipment readily available in case of anaphylaxis.
• Observe for anaphylaxis. People with no history of hypersensitivity may have allergic response.
• Assess for signs of superinfection (eg, bacterial or fungal overgrowth of nonsusceptible organisms).
• Monitor newborns closely for signs of toxicity or adverse effects.
• Monitor renal function, especially in patients with renal impairment. Monitor I&O strictly. If urinary output is decreased, notify health care provider.
• If patient develops rash, pruritus, laryngeal edema, evidence of hemolysis, wheezing, or other signs of allergic reaction, discontinue drug and notify health care provider.
• If sudden elevation in temperature develops, notify health care provider; it may be drug fever.
• Discontinue penicillin G if signs of hemolytic anemia develop (positive Coomb's test).

 Patient/Family Education

• Instruct patient to finish course of therapy even if feeling better.
• Advise patient to take oral penicillin at intervals around clock on empty stomach 1 hr before or 2 hr after meal with full glass of water, not fruit juice or carbonated beverage.
• Instruct penicillin allergic patient to carry Medi-Alert necklace or bracelet.
• Advise patient to use nonhormonal form of contraceptive while taking penicillin.
• Inform patient of signs of hypersensitivity (eg, skin rash, itching, hives, shortness of breath, wheezing) and other side effects, such as black tongue, sore throat, nausea, vomiting, severe diarrhea, fever, swollen joints, and instruct patient to notify health care provider should they occur.
• Instruct patient to notify health care provider if there is no improvement in symptoms of infection.
• Advise patient to notify health care provider of signs of superinfection (eg, vaginitis, black “hairy” tongue).

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Copyright © 2003 Facts and Comparisons
David S. Tatro
A to Z Drug Facts