MINOCIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for MINOCIN (MINOCIN).
Minocycline is a tetracycline antibiotic that inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit, blocking the binding of aminoacyl-tRNA to the mRNA-ribosome complex.
| Metabolism | Primarily hepatic via CYP3A4; also undergoes enterohepatic recycling. |
| Excretion | Primarily renal (approximately 70% unchanged) and biliary/fecal (approximately 30%, with enterohepatic recycling). |
| Half-life | Terminal elimination half-life is 11–17 hours in patients with normal renal function; prolonged up to 18–69 hours in renal impairment. |
| Protein binding | 65–75% bound to serum proteins. |
| Volume of Distribution | Vd approximately 1.3 L/kg, indicating extensive tissue distribution. |
| Bioavailability | Oral: 90–100% |
| Onset of Action | Oral: 1–4 hours; Intravenous: within minutes to 1 hour. |
| Duration of Action | 12–24 hours; clinical effect persists for 24 hours with twice-daily dosing. |
| Molecular Weight | 457.5 |
| Action Class | Aminoglycosides |
| Brand Substitutes | Amilab 500mg Injection, Acil 500mg Injection, Emica 500mg Injection, Mika Best 500mg Injection, Ivimicin 500mg Injection, Mkcin 100mg Injection, Amikanex 100mg Injection, Mbkacin 100mg Injection, Megamika 100mg Injection, Mikabit 100mg Injection, Cachmik 250mg Injection, Amikas 250mg Injection, Amibiotic 250mg Injection, Amister 250mg Injection, Ivimicin 250mg Injection |
100 mg orally or intravenously every 12 hours for 24 hours, then 100 mg every 12 hours; severe infections: 200 mg initially, then 100 mg every 12 hours.
| Dosage form | SUSPENSION |
| Renal impairment | No adjustment required for mild to moderate renal impairment. Not recommended in severe renal impairment (CrCl <10 mL/min) due to anti-anabolic effect; use alternative if possible. For CrCl 10-50 mL/min, consider reducing dose or extending interval (e.g., 100 mg every 24 hours). See prescribing information. |
| Liver impairment | Child-Pugh A: No adjustment. Child-Pugh B: Use with caution; consider dose reduction (e.g., 50 mg every 12 hours) due to reduced clearance. Child-Pugh C: Avoid use or reduce to 50 mg every 12 hours with close monitoring. |
| Pediatric use | Children ≥8 years: 4 mg/kg orally or IV initially, followed by 2 mg/kg every 12 hours. Maximum single dose: 200 mg. For children <8 years: not recommended due to risk of permanent tooth discoloration. |
| Geriatric use | Elderly patients may have reduced renal function; monitor renal status and adjust dose accordingly (see renal adjustment). No specific dose reduction needed with normal renal function, but consider lower starting dose (e.g., 50 mg every 12 hours) due to increased sensitivity and potential for photosensitivity. |
| 1st trimester | Contraindicated; associated with inhibition of bone growth and discoloration of deciduous teeth. Use only for serious infections where alternatives are ineffective or contraindicated. |
| 2nd trimester | Contraindicated; same risks as t1. Risk of skeletal development abnormalities and permanent tooth discoloration. |
| 3rd trimester | Contraindicated; same risks as t1. Potential for hepatotoxicity in pregnant patients. |
Clinical note
Comprehensive clinical and safety monograph for MINOCIN (MINOCIN).
| Placental transfer | Minocycline crosses the placenta via passive diffusion and active transport. Fetal serum levels reach approximately 25-75% of maternal concentrations. |
| Breastfeeding | Minocycline is excreted into human milk at low concentrations. Theoretical risk of bone and dental effects in nursing infants. Use only if no safer alternative is available; consider temporary cessation of breastfeeding. |
■ FDA Black Box Warning
None.
| Serious Effects |
Hypersensitivity to minocycline or any tetracyclineChildren under 8 years of age (permanent tooth discoloration, enamel hypoplasia, bone growth inhibition)Pregnancy (except for anthrax or other life-threatening infections where benefit outweighs risk)Breastfeeding (if prolonged exposure is expected)
| Precautions | Hepatotoxicity (including autoimmune hepatitis), Central nervous system effects (dizziness, vertigo, ataxia), Photosensitivity, Intracranial hypertension (pseudotumor cerebri), Esophageal ulceration, Tooth discoloration and enamel hypoplasia in children under 8 years, Fetal harm if used during pregnancy, Clostridioides difficile-associated diarrhea, Superinfection with resistant organisms |
| Food/Dietary | Avoid dairy products (milk, cheese, yogurt) within 2 hours of taking minocycline as calcium reduces absorption. Avoid concurrent use with iron supplements, antacids (aluminum, calcium, magnesium), and zinc supplements. High-fat meals may decrease absorption; take on an empty stomach if possible. |
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| Lactation Rating | L3 (Moderately Safe) - or 'Avoid' depending on assessment; American Academy of Pediatrics considers compatible but caution advised. |
| Teratogenic Risk | Pregnancy Category D. Avoid in pregnancy. Tetracyclines, including minocycline, cross the placenta and can cause permanent discoloration of teeth (yellow-gray-brown) and reversible inhibition of bone growth during the second and third trimesters. First trimester use is associated with a small increased risk of neural tube defects and cardiovascular malformations, but data are limited. Use during the second and third trimesters is contraindicated due to dental and skeletal effects. |
| Fetal Monitoring | Maternal: Monitor liver function tests (hepatotoxicity) and renal function; assess for symptoms of pseudotumor cerebri (headache, visual changes). Fetal: Ultrasound monitoring for skeletal growth and dental development if exposure occurs in second or third trimester. No routine fetal monitoring is recommended for first trimester exposure, but pregnancy should be followed for potential congenital anomalies. |
| Fertility Effects | Minocycline may cause reversible male infertility due to effects on sperm motility and morphology; in females, no significant impact on fertility has been reported. Caution in patients attempting conception; consider alternative antibiotics during fertility treatment. |
| Clinical Pearls | Minocin (minocycline) is a tetracycline antibiotic with high tissue penetration, especially into the CNS and sebum. It is photosensitizing; avoid sun exposure. Use with caution in hepatic impairment and patients with autoimmune disorders due to risk of drug-induced lupus. Minocycline can cause vestibular toxicity (dizziness, ataxia) more than other tetracyclines. Avoid in children <8 years and pregnant women due to bone/tooth effects. Blue-gray skin pigmentation may occur with long-term use. |
| Patient Advice | Take exactly as prescribed; finish the full course even if you feel better. · Take with a full glass of water to reduce risk of esophageal irritation. · Avoid taking with dairy products, antacids, or iron supplements within 2 hours. · Do not take if you are pregnant, breastfeeding, or planning to become pregnant. · Use sunscreen and protective clothing; avoid prolonged sun exposure. · Report severe headache, vision changes, joint pain, or yellowing of skin/eyes. · This medicine may cause dizziness or lightheadedness; avoid driving until you know how it affects you. · Do not use after expiration date; discard unused medication properly. |