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. |
| Molecular Weight | 891.09 |
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 | Avoid; associated with congenital anomalies (e.g., cleft palate, limb defects) in animal studies and human case reports; use only if no alternative. |
| 2nd trimester | Avoid; potential for maternal hepatotoxicity and risks to fetus; use only if no alternative. |
| 3rd trimester | Avoid; risk of fetal hepatotoxicity and gray baby syndrome; use only if no alternative. |
Clinical note
Comprehensive clinical and safety monograph for PANMYCIN (PANMYCIN).
| Placental transfer | Crosses placenta readily; achieves fetal serum concentrations 50–60% of maternal levels. |
| Breastfeeding | Excreted into breast milk in low concentrations; potential for infant gut flora alteration and sensitization; caution recommended; use only if benefit outweighs risk. |
■ 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 tetracyclinesSevere hepatic impairmentConcurrent use with retinoids (e.g., isotretinoin) due to increased risk of pseudotumor cerebri
| Precautions | Photosensitivity with exaggerated sunburn; hepatotoxicity; renal impairment; superinfection; esophagitis; intracranial hypertension; use in pregnancy and children under 8 years. |
| Food/Dietary | Avoid dairy products (milk, cheese, yogurt), antacids containing aluminum/calcium/magnesium, iron-containing products, and multivitamins containing minerals. These chelate tetracycline and significantly reduce absorption. Alcohol may decrease efficacy and increase hepatotoxicity risk. |
Loading safety data…
| Lactation Rating |
| L3 (Moderately Safe) or 'Caution' |
| 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. |
| 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. |
| Clinical Pearls | PANMYCIN (tetracycline) is bacteriostatic and should not be used in severe infections requiring bactericidal agents. Avoid in pregnancy (category D), children <8 years, and patients with hepatic impairment. Administer on an empty stomach 1 hour before or 2 hours after meals. Monitor for photosensitivity, superinfection, and pseudotumor cerebri. Discontinue if renal function declines. |
| Patient Advice | Take this medication on an empty stomach with a full glass of water 1 hour before or 2 hours after meals. · Avoid dairy products, antacids, iron supplements, and multivitamins within 2 hours of taking this drug as they can reduce absorption. · Do not take if you are pregnant, planning to become pregnant, or breastfeeding. This can cause permanent tooth discoloration in children. · Use sunscreen and protective clothing to avoid severe sunburn; avoid prolonged sun exposure and tanning beds. · Complete the full course even if you feel better; do not skip doses. · Report any severe headache, blurred vision, or skin rash immediately. |