penicillin V potassium
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penicillin V potassium
Pharmacologic class: Penicillin
Therapeutic class: Anti-infective
Pregnancy risk category B
Action
Inhibits biosynthesis of cell-wall mucopeptide; bactericidal against penicillin-susceptible microorganisms during active multiplication stage
Availability
Oral solution: 200,000 units (125 mg)/5 ml, 400,000 units (250 mg)/5 ml
Tablets: 400,000 units (250 mg), 800,000 units (500 mg)
Indications and dosages
➣ Upper respiratory streptococcal infections, including scarlet fever and mild erysipelas
Adults and children ages 12 and older: 125 to 250 mg P.O. q 6 to 8 hours for 10 days
Children younger than age 12: 25 to 50 mg/kg/day P.O. in divided doses q 6 hours for 10 days
➣ Pneumococcal respiratory infections, including otitis media
Adults and children ages 12 and older: 250 to 500 mg P.O. q 6 hours until afebrile for at least 2 days
➣ Skin and soft-tissue staphylococcal infections; fusospirochetosis (Vincent's infection) of oropharynx
Adults and children ages 12 and older: 250 to 500 mg P.O. q 6 to 8 hours
➣ To prevent recurrence of rheumatic fever or chorea
Adults and children ages 12 and older: 125 to 250 mg P.O. b.i.d. on a continuing basis
Off-label uses
• Prophylaxis of Streptococcus pneumoniae septicemia in children with sickle cell anemia or splenectomy
• Early Lyme disease
• Actinomycosis
• Preexposure prophylaxis of anthrax
• Prophylaxis of bacterial endocarditis for dental procedures
Contraindications
• Hypersensitivity to penicillins or beta-lactamase inhibitors (piperacillin/tazobactam)
Precautions
Use cautiously in:
• severe renal insufficiency
• pregnant or breastfeeding patients.
Administration
• Before giving, ask patient about allergies to penicillin, beta-lactamase inhibitors, or benzathine. Know that cross-sensitivity to imipenem and cephalosporins may occur.
☞ Keep epinephrine and emergency equipment at hand in case anaphylaxis occurs.
• Give with water 1 hour before or 2 hours after meals. Don't give with fruit juice or carbonated beverages.
Adverse reactions
CNS: lethargy, hallucinations, anxiety, depression, twitching, seizures, coma
GI: nausea, vomiting, diarrhea, epigastric distress, abdominal pain, colitis, blood in stool, glossitis, pseudomembranous colitis
GU: interstitial nephritis
Hematologic: anemia, hemolytic anemia, increased bleeding, leukopenia, granulocytopenia, bone marrow depression, thrombocytopenia, thrombocytopenic purpura
Metabolic: hypokalemia, hyperkalemia, metabolic alkalosis
Skin: rash, urticaria
Other: fever, superinfection, 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: increased levels Albumin, lymphocytes, protein, sodium, uric acid, white blood cells: decreased levels
Direct Coombs' test: positive result
Potassium: increased or decreased level
Urine glucose, urine protein: false-positive results
Drug-herbs. Khat: delayed and reduced penicillin absorption
Patient monitoring
☞ Watch 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.
☞ Monitor patient closely for signs and symptoms of superinfection and pseudomembranous colitis.
Patient teaching
• Instruct patient to take with water 1 hour before or 2 hours after meals. Tell him not to take with fruit juice or carbonated beverages.
☞ Teach patient to recognize anaphylaxis symptoms. Tell him to immediately contact emergency medical services if these occur.
• Instruct patient to report signs and symptoms of superinfection.
• Advise patient to contact prescriber if infection symptoms get worse.
☞ Tell patient drug may cause diarrhea. Instruct him to immediately report severe, persistent diarrhea and fever.
• Instruct patient to complete entire course of therapy as prescribed, even after symptoms improve.
• Tell female patient drug may make hormonal contraceptives ineffective. Advise 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, tests, and herbs mentioned above.