penicillin G procaine

Action

Inhibits biosynthesis of cell-wall mucopeptide; bactericidal against penicillin-susceptible microorganisms during active multiplication stage

Availability

Suspension for I.M. injection: 600,000 units/ml vial, 1.2 million units/2-ml vial, 2.4 million units/4-ml vial, 3 million units/10-ml vial

Indications and dosages

➣ Anthrax; bacterial endocarditis; erysipeloid and fusospirochetal infections; group A streptococcal infections; moderately severe, uncomplicated pneumococcal pneumonia and staphylococcal infections; rat-bite fever

Adults: 600,000 to 1 million units/day I.M.

➣ Diphtheria

Adults: 300,000 to 600,000 units/day I.M. given with antitoxin for 14 days. For carrier state, 300,000 units/day I.M. for 10 days.

➣ Syphilis, yaws, bejel, pinta

Adults and children older than age 12: 600,000 units/day I.M. for 8 days; for late infections, continue for 10 to 15 days. For neurosyphilis, 2.4 million units/day I.M. for 10 to 14 days, given with probenecid.

➣ Congenital syphilis

Children: 50,000 units/kg I.M. daily for at least 10 days

➣ Uncomplicated gonorrhea

Adults: 4.8 million units/day I.M., divided into at least two doses and two sites at one visit, with P.O. probenecid given 30 minutes before injection

Off-label uses

• Lyme disease

• Predental prophylaxis against bacterial endocarditis

Contraindications

• Hypersensitivity to penicillins, beta-lactamase inhibitors (piperacillin/tazobactam), or procaine

Precautions

Use cautiously in:

• severe renal insufficiency, significant allergies, asthma

• pregnant or breastfeeding patients

• neonates.

Administration

• Before giving, ask patient about allergy to penicillin, beta-lactamase inhibitors, or benzathine. Know that cross-sensitivity to imipenem and cephalosporins may occur.

See Keep epinephrine and emergency equipment at hand in case anaphylaxis occurs.

• In adults, inject I.M. deep into upper outer aspect of buttock.

• In infants and small children, inject at a slow, steady rate into midlateral aspect of thigh.

• Be aware that Hoigne's syndrome (transient bizarre behavior and neurologic reactions) may immediately follow I.M. injection.

• Know that in syphilis treatment, Jarisch-Hersheimer reaction (fever, chills, headache, sweating, malaise, hypotension or hypertension) may occur 2 to 12 hours after therapy starts and usually subsides within 24 hours.

Adverse reactions

CNS: lethargy, hallucinations, anxiety, depression, twitching, Hoigne's syndrome, seizures, coma

EENT: laryngeal edema

GI: nausea, vomiting, diarrhea, epigastric distress, abdominal pain, colitis, blood in stool, glossitis, pseudomembranous colitis

GU: interstitial nephritis

Hematologic: increased bleeding, hemolytic anemia, bone marrow depression, leukopenia, thrombocytopenia, granulocytopenia

Skin: rash, urticaria

Other: pain at I.M. injection site, fever, superinfection, Jarisch-Hersheimer reaction, sterile abscess, procaine toxicity, anaphylaxis, serum sickness

Interactions

Drug-drug. Aspirin, probenecid: increased penicillin blood level

Erythromycins, tetracyclines: decreased antimicrobial activity of penicillin

Hormonal contraceptives: decreased contraceptive efficacy

Drug-diagnostic tests. Alanine aminotransferase, eosinophils, granulocytes, hemoglobin, platelets, potassium, white blood cells: increased levels

Direct Coombs' test: positive result

Sodium: decreased level

Urine glucose, urine protein: false-positive results

Patient monitoring

See Watch closely for signs and symptoms of anaphylaxis and serum sickness.

• In long-term therapy, monitor electrolyte levels and CBC with white cell differential. Watch for electrolyte imbalances and blood dyscrasias.

• Assess neurologic status, especially for seizures and decreasing level of consciousness.

See Monitor patient for signs and symptoms of superinfection and pseudomembranous colitis.

Patient teaching

See Teach patient to recognize signs and symptoms of anaphylaxis. Tell him to contact emergency medical services immediately if these occur.

See Tell patient drug may cause diarrhea. Instruct him to immediately report severe, persistent diarrhea and fever.

• Stress importance of completing entire course of therapy as prescribed, even after symptoms improve.

• Advise patient to contact prescriber if infection symptoms worsen.

• Tell female patient that drug may make hormonal contraceptives ineffective. Encourage her to use barrier birth-control method if she wishes to avoid pregnancy.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs and tests mentioned above.