PENICILLIN-VK
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PENICILLIN-VK (PENICILLIN-VK).
Penicillin VK inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), inhibiting transpeptidase activity, and activating autolytic enzymes.
| Metabolism | Hepatic metabolism to inactive metabolites (minor pathway); primarily excreted unchanged in urine via renal tubular secretion. |
| Excretion | Renal: 20-40% unchanged via tubular secretion; hepatic metabolism to penicilloic acid; biliary/fecal: minimal (<5%). |
| Half-life | 0.5 hours (normal renal function); prolonged to 3-10 hours in severe renal impairment (CrCl <10 mL/min). |
| Protein binding | 60-80% bound to serum albumin. |
| Volume of Distribution | 0.3-0.4 L/kg; reflects distribution into extracellular fluid and limited tissue penetration except in inflamed meninges. |
| Bioavailability | Oral: 60-75% (varies with food intake; reduced by presence of food). |
| Onset of Action | Oral: 30-60 minutes; IM: 15-30 minutes; rapid bactericidal effect. |
| Duration of Action | 4-6 hours (oral); 6-8 hours (IM); clinical effect may persist up to 12 hours in renal impairment. |
250-500 mg orally every 6-8 hours for mild to moderate infections; 500 mg orally every 6 hours for severe infections (e.g., streptococcal pharyngitis, skin infections).
| Dosage form | TABLET |
| Renal impairment | No adjustment needed for GFR >50 mL/min. For GFR 10-50 mL/min: administer every 8-12 hours. For GFR <10 mL/min: administer every 12-16 hours. Hemodialysis: 500 mg after dialysis. |
| Liver impairment | No dose adjustment required for Child-Pugh Class A or B. For Child-Pugh Class C: use with caution; consider dose reduction based on clinical response (limited data). |
| Pediatric use | For children weighing <40 kg: 25-50 mg/kg/day orally divided every 6-8 hours; maximum 3 g/day. For children weighing ≥40 kg: adult dosing applies. |
| Geriatric use | No specific dose adjustment recommended; use lowest effective dose due to age-related renal function decline. Monitor renal function and adjust per renal adjustment guidelines. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for PENICILLIN-VK (PENICILLIN-VK).
| Breastfeeding | Penicillin VK is excreted into human breast milk in trace amounts. The milk-to-plasma (M/P) ratio is approximately 0.08–0.13. The American Academy of Pediatrics considers penicillin VK compatible with breastfeeding. Potential for allergic sensitization or diarrhea in the infant exists, but clinical significance is low. |
| Teratogenic Risk | Penicillin VK (phenoxymethylpenicillin) is classified as FDA Pregnancy Category B. Animal reproduction studies have not demonstrated a risk to the fetus, and there are no adequate and well-controlled studies in pregnant women. However, penicillin antibiotics are generally considered safe during pregnancy. No known teratogenic effects have been associated with penicillin VK in any trimester. Use during pregnancy should be reserved for clear indications. |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
["Hypersensitivity to penicillins or any component of the formulation.","Previous immediate hypersensitivity reaction (e.g., anaphylaxis, Stevens-Johnson syndrome) to a penicillin or beta-lactam antibiotic."]
| Precautions | ["Serious hypersensitivity reactions (anaphylaxis) can occur; contraindicated in patients with prior penicillin allergy.","Superinfection with resistant organisms may develop with prolonged use.","Use with caution in patients with renal impairment (dose adjustment may be needed).","Assess renal, hepatic, and hematologic function periodically during prolonged therapy.","May interfere with oral contraceptives; alternative contraception recommended."] |
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| Fetal Monitoring | No specific maternal-fetal monitoring is required beyond standard clinical assessment. Monitor for allergic reactions, including rash and anaphylaxis. In long-term therapy, assess renal function and complete blood count periodically. For fetal monitoring, no special surveillance is indicated. |
| Fertility Effects | Penicillin VK has no known adverse effects on fertility in animal studies or human data. No impact on spermatogenesis or oogenesis has been reported. |