PANMYCIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PANMYCIN (PANMYCIN).
Tetracycline antibiotic that inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit, preventing aminoacyl-tRNA from attaching to the A site.
| Metabolism | Not extensively metabolized; primarily excreted unchanged in urine via glomerular filtration. |
| Excretion | Primarily renal excretion of unchanged drug via glomerular filtration; 80-90% recovered in urine within 24 hours. Biliary/fecal excretion accounts for <5%. |
| Half-life | Terminal elimination half-life is 6-8 hours in patients with normal renal function. Half-life is significantly prolonged (up to 80 hours) in anuria, requiring dose adjustment. |
| Protein binding | Approximately 65-75% bound to serum proteins, primarily albumin. |
| Volume of Distribution | Volume of distribution is 0.5-0.7 L/kg, indicating distribution into total body water; does not cross blood-brain barrier in non-inflamed meninges. |
| Bioavailability | Oral: 60-80%, reduced by food; intramuscular: 70-85%, with variable absorption due to local irritation. |
| Onset of Action | Intravenous: within 1 hour; intramuscular: 2-4 hours; oral: 4-6 hours. Onset delayed in patients with impaired absorption or severe infection. |
| Duration of Action | Intravenous: 12-24 hours; intramuscular: 12-24 hours; oral: 12 hours. Duration is prolonged in renal impairment and with higher doses. |
250-500 mg PO q6h or 500 mg to 1 g IV q6h; maximum 4 g/day
| Dosage form | TABLET |
| Renal impairment | CrCl 50-80 mL/min: administer q8-12h; CrCl 10-50 mL/min: administer q12-24h; CrCl <10 mL/min: administer q24-48h |
| Liver impairment | No specific adjustment; use caution in severe hepatic impairment |
| Pediatric use | 25-50 mg/kg/day PO divided q6h; 20-40 mg/kg/day IV divided q6h |
| Geriatric use | Reduce dose based on renal function; monitor for ototoxicity and nephrotoxicity |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for PANMYCIN (PANMYCIN).
| Breastfeeding | Panmycin is excreted in breast milk in low concentrations (M/P ratio approximately 0.5-1.0). Theoretical risk of dental staining and bone growth suppression in nursing infants. American Academy of Pediatrics considers use compatible with breastfeeding, but alternative agents preferred. Monitor infant for rash, diarrhea, and oral thrush. |
| Teratogenic Risk | Panmycin (tetracycline) is contraindicated in pregnancy. First trimester: animal studies show teratogenic effects (skeletal malformations), human data limited; risk cannot be excluded. Second and third trimesters: causes permanent tooth discoloration (yellow-gray-brown) and enamel hypoplasia in fetus; also inhibits fetal bone growth. Use of tetracyclines during tooth development (last half of pregnancy) is associated with dental staining. |
■ FDA Black Box Warning
Use during tooth development (last half of pregnancy, infancy, and childhood to age 8 years) may cause permanent discoloration of teeth (yellow-gray-brown).
| Serious Effects |
Hypersensitivity to tetracyclines; severe hepatic or renal impairment; pregnancy; lactation; children under 8 years.
| Precautions | Photosensitivity with exaggerated sunburn; hepatotoxicity; renal impairment; superinfection; esophagitis; intracranial hypertension; use in pregnancy and children under 8 years. |
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| Fetal Monitoring | Monitor maternal liver function, renal function, and complete blood count periodically. In pregnancy, avoid use; if exposure occurs, monitor fetal growth and development via ultrasound. In neonates, monitor for signs of increased intracranial pressure (bulging fontanelles) and bone growth. |
| Fertility Effects | Tetracyclines may impair fertility in both sexes. In males, they can reduce sperm motility and count. In females, they may cause vaginal candidiasis, potentially affecting fertility. Animal studies show reduced fertility at high doses. Human data limited. |