penicillin V potassium
Apo-Pen VK ◆, Beepen-VK, Nadopen-V ◆, Novo-Pen-VK ◆, Nu-Pen-VK ◆, Pen-Vee K, PVF K ◆, V-Cillin K, Veetids

Available forms
Available by prescription only
Solution: 125 mg/5 ml, 250 mg/5 ml (after reconstitution)
Tablets: 250 mg, 500 mg
Tablets (film-coated): 250 mg, 500 mg

Indications and dosages
 Mild to moderate susceptible infections. Adults and children ages 12 and older: 125 to 500 mg (200,000 to 800,000 units) P.O. q 6 hours.
Children ages 1 month to 12 years: 15 to 62.5 mg/kg P.O. daily, divided into doses given q 6 to 8 hours.
 Necrotizing ulcerative gingivitis. Adults: 250 to 500 mg P.O. q 6 to 8 hours.
 Lyme disease ◇. Adults: 250 to 500 mg P.O. q.i.d. for 10 to 20 days.
 Prophylaxis for pneumococcal infection ◇.
Adults: 250 mg P.O. b.i.d.
Children older than age 5: 125 mg P.O. b.i.d.

Pharmacodynamics
Antibiotic action: Bactericidal. Adheres to penicillin-binding proteins, thus inhibiting bacterial cell wall synthesis. Spectrum of activity includes most non-penicillinase-producing strains of gram-positive and gram-negative aerobic cocci, spirochetes, and some gram-positive aerobic and anaerobic bacilli.

Pharmacokinetics
Absorption: Penicillin V has greater acid stability and is absorbed more completely than penicillin G after oral administration. About 60% to 75% of oral dose of penicillin V absorbed. Serum levels peak at 60 minutes in fasting subjects; food has no significant effect.
Distribution: Distributed widely into synovial, pleural, pericardial, and ascitic fluids and into bile, liver, skin, lungs, kidneys, muscle, intestines, tonsils, maxillary sinuses, saliva, and erythrocytes. CSF penetration is poor but enhanced in patients with inflamed meninges. Penicillin V crosses the placental barrier and is 75% to 89% protein-bound.
Metabolism: Between 35% and 70% is metabolized to inactive compounds.
Excretion: Excreted primarily in urine by tubular secretion; 26% to 65% of dose recovered in 6 hours. Some drug appears in breast milk. Elimination half-life in adults is 1/2 hour; severe renal impairment prolongs half-life.

Contraindications and precautions
Contraindicated in patients hypersensitive to drug or other penicillins. Use cautiously in patients with drug allergies (especially to cephalosporins or imipenem).

Interactions
Drug-drug. Aminoglycosides: Causes synergistic therapeutic effects, chiefly against enterococci. However, drugs are physically and chemically incompatible; inactivated when given together. Don’t administer together.
Anticoagulants, heparin: Increases risk of bleeding. Monitor PTT, PT, and INR.
Hormonal contraceptives that contain estrogen: Decreases efficacy; may cause breakthrough bleeding. Suggest alternative method of contraception.
Probenecid: Blocks tubular secretion of penicillin; increases serum levels of drug. Probenecid may be used for this purpose.
Sulfinpyrazone: Prolongs penicillin V half-life. Watch for clinical effectiveness.
Drug-herb. Guar gum: Decreases absorption of orally administered drugs. Advise patient to take drug 1 hour before or several hours after guar gum.

Adverse reactions
CNS: neuropathy.
GI: epigastric distress, vomiting, diarrhea, nausea, black "hairy" tongue.
GU: nephropathy.
Hematologic: eosinophilia, hemolytic anemia, leukopenia, thrombocytopenia.
Other: hypersensitivity reactions (rash, urticaria, fever, laryngeal edema, anaphylaxis ), overgrowth of nonsusceptible organisms.

Effects on lab test results
• May increase eosinophil count. May decrease hemoglobin, hematocrit, and platelet, WBC, and granulocyte counts.

Overdose and treatment
Signs and symptoms of overdose include neuromuscular sensitivity and seizures.
 No specific recommendations are available. Treatment is supportive. After recent ingestion (within 4 hours), empty stomach by induced emesis or gastric lavage; follow with activated charcoal to reduce absorption.

Special considerations
 ALERT Don’t confuse the various types of penicillin, polycillin, and penicillamine.
• Give oral dose 1 hour before or 2 hours after meals for maximum absorption.
• After reconstitution, oral solution is stable for 14 days if refrigerated.
• Monitor patient for overgrowth of nonsusceptible organisms.
• Penicillin V alters test results for urine and serum protein levels and interferes with turbidimetric methods using sulfosalicylic acid, trichloroacetic acid, acetic acid, and nitric acid. Penicillin V doesn’t interfere with tests using bromophenol blue (Albustix, Albutest, Multistix) and may falsely decrease serum aminoglycoside levels.
Breast-feeding patients
• Drug appears in breast milk. Use in breast-feeding women may sensitize infant to penicillins.
Geriatric patients
• Half-life may be prolonged in elderly patients because of impaired renal function.

Patient education
• Tell patient to take drug on an empty stomach for maximum absorption.
• Tell patient to complete full course of therapy even if feeling better.

Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE THREATENING.
◆ Canada only
◇ Unlabeled clinical use