PENAPAR-VK
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PENAPAR-VK (PENAPAR-VK).
Penicillin V is a bactericidal antibiotic that inhibits cell wall synthesis by binding to penicillin-binding proteins (PBPs), inhibiting transpeptidation, and activating autolytic enzymes.
| Metabolism | Penicillin V is primarily metabolized by hydrolysis to penicilloic acid, which is inactive. Minor hepatic metabolism occurs. Approximately 60-80% is excreted unchanged in urine. |
| Excretion | Primarily renal excretion (tubular secretion) of unchanged drug (~90%); minor biliary/fecal elimination (<10%). |
| Half-life | Terminal elimination half-life: 0.5–1 hour in normal renal function; prolonged to 7–10 hours in severe renal impairment (anuria). Requires dose adjustment in renal failure. |
| Protein binding | ~80% bound primarily to albumin. |
| Volume of Distribution | 0.2–0.3 L/kg; limited distribution due to high protein binding and rapid renal clearance; does not cross blood-brain barrier significantly in absence of inflammation. |
| Bioavailability | Oral: 60–73% (variable due to food effect; take on empty stomach). |
| Onset of Action | Oral: 30–60 minutes (peak serum concentration at 1 hour); IM: 15–30 minutes; IV: immediate. |
| Duration of Action | 6–8 hours for susceptible organisms; may persist longer if renal impairment present. Rebound bacteriostatic effect noted up to 2–4 hours after serum levels fall below MIC. |
| Molecular Weight | 350.39 |
250-500 mg orally every 6 hours; maximum 2 g/day.
| Dosage form | FOR SOLUTION |
| Renal impairment | CrCl <10 mL/min: 250 mg every 12 hours; CrCl 10-50 mL/min: 250-500 mg every 6-8 hours. |
| Liver impairment | No adjustment required for mild to moderate impairment; use caution in severe impairment. |
| Pediatric use | Neonates: 20-30 mg/kg/day divided every 12 hours; Infants and children: 25-50 mg/kg/day divided every 6 hours; maximum 3 g/day. |
| Geriatric use | No specific adjustment required; monitor renal function and adjust accordingly based on CrCl. |
| 1st trimester | Penicillin V is generally considered safe in the first trimester. Animal studies have not shown fetal risk, and there are no well-controlled studies in pregnant women. Use only if clearly needed. |
| 2nd trimester | Penicillin V is considered safe in the second trimester. It crosses the placenta but has not been associated with fetal harm. |
| 3rd trimester | Penicillin V is considered safe in the third trimester. Use near term may theoretically affect neonatal gut flora, but no adverse outcomes have been documented. |
Clinical note
Comprehensive clinical and safety monograph for PENAPAR-VK (PENAPAR-VK).
| Placental transfer | Penicillin V crosses the placenta. Fetal serum concentrations are approximately 20-50% of maternal serum concentrations. |
| Breastfeeding | Penicillin V is excreted into breast milk in small amounts (estimated 0.2% of maternal dose). It is generally considered compatible with breastfeeding. However, potential for alteration of infant gut flora and allergic sensitization exists. Monitor infant for rash, diarrhea, or candidiasis. |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
Hypersensitivity to penicillinsHistory of immediate hypersensitivity reaction to cephalosporinsPhenylketonuria (due to phenylalanine content in some formulations)
| Precautions | Serious and occasionally fatal hypersensitivity reactions (anaphylaxis) can occur., Clostridium difficile-associated diarrhea (CDAD) may develop., Use with caution in patients with renal impairment due to risk of neurotoxicity., Prolonged use may result in superinfection., Use with caution in patients with a history of allergy, asthma, or hay fever. |
| Food/Dietary | Take on an empty stomach; food, especially high-fat meals, can decrease absorption. No specific food interactions listed, but avoid acidic beverages (e.g., fruit juices) within 1 hour of dosing as they may affect stability. |
Loading safety data…
| Lactation Rating | L1 (Safe) |
| Teratogenic Risk | FDA Pregnancy Category B. Penicillin VK crosses the placenta. No evidence of teratogenicity in animal studies. First trimester: theoretical risk due to alterations in gut flora, but no known teratogenic effects. Second and third trimesters: safe for treatment of infections; avoid high doses near term due to risk of neonatal hemolytic anemia or sensitization. |
| Fetal Monitoring | Monitor maternal renal function and CBC. In pregnancy, assess for signs of infection resolution. No specific fetal monitoring required except when used for group B Streptococcus prophylaxis during labor (standard intrapartum monitoring). |
| Fertility Effects | No known adverse effects on fertility in animal or human studies. Penicillin VK does not affect spermatogenesis, ovulation, or implantation. |
| Clinical Pearls | Penicillin V potassium should be taken on an empty stomach (1 hour before or 2 hours after meals) for optimal absorption; avoid concomitant use with bacteriostatic antibiotics (e.g., tetracyclines) as they may antagonize bactericidal effect; monitor renal function in elderly or those with renal impairment to adjust dose; be aware of cross-allergenicity with cephalosporins in penicillin-allergic patients (though risk is low); use with caution in patients with history of seizures due to potential neurotoxicity with high doses; for streptococcal pharyngitis, treat for full 10 days to prevent rheumatic fever. |
| Patient Advice | Take this medication exactly as prescribed, usually 4 times a day. · Take on an empty stomach, at least 1 hour before or 2 hours after meals. · Complete the full course of therapy even if you feel better to prevent resistance. · Shake the oral suspension well before each dose. · If you miss a dose, take it as soon as possible; skip if almost time for next dose; do not double. · Notify your doctor if you develop rash, hives, difficulty breathing, severe diarrhea, or oral thrush. · Store at room temperature; for oral suspension, check specific storage instructions (may need refrigeration). · Avoid alcohol while taking this medication to reduce risk of adverse effects. |