ACHROMYCIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ACHROMYCIN (ACHROMYCIN).
Tetracycline antibiotic that inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit, preventing aminoacyl-tRNA from binding to the A site.
| Metabolism | Primarily renally excreted unchanged; minimal hepatic metabolism. |
| Excretion | Renal (60-80% unchanged via glomerular filtration); biliary/fecal (10-20%) |
| Half-life | 6-12 hours; prolonged to 48-72 hours in severe renal impairment |
| Protein binding | 50-60% bound to serum proteins |
| Volume of Distribution | 1.5-2.0 L/kg; indicates extensive tissue penetration |
| Bioavailability | Oral: 75-80%; Topical: minimal systemic absorption |
| Onset of Action | Oral: 1-2 hours; IV: immediate; Topical: within 24-48 hours |
| Duration of Action | Oral/IV: 6-12 hours; Topical: sustained during application |
250-500 mg orally every 6 hours or 500 mg intravenously every 12 hours.
| Dosage form | INJECTABLE |
| Renal impairment | GFR 50-80 mL/min: no adjustment; GFR 10-50 mL/min: administer every 12-24 hours; GFR <10 mL/min: administer every 24 hours or avoid. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: avoid use. |
| Pediatric use | 25-50 mg/kg/day orally divided every 6 hours; maximum 2 g/day. |
| Geriatric use | Initiate at lower end of dosing range due to age-related renal function decline; monitor renal function. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ACHROMYCIN (ACHROMYCIN).
| Breastfeeding | Tetracycline is excreted into breast milk in low concentrations. Theoretical risk of dental discoloration and bone growth suppression in nursing infants, but levels are usually below therapeutic. M/P ratio is approximately 0.5-0.8. Use with caution, especially in infants with prolonged exposure. American Academy of Pediatrics considers tetracyclines compatible with breastfeeding. |
| Teratogenic Risk | ACHROMYCIN (tetracycline) is classified as FDA Pregnancy Category D. First trimester: Associated with minor malformations, but risk is low. Second and third trimesters: Exposure can cause permanent discoloration of deciduous teeth (yellow-gray-brown) due to deposition during calcification, and reversible inhibition of bone growth. Avoid use after the fourth month of pregnancy. Risk of maternal hepatotoxicity if used intravenously in pregnancy. |
■ FDA Black Box Warning
No FDA boxed warning
| Serious Effects |
["Hypersensitivity to tetracyclines","Pregnancy (second and third trimesters) due to fetal harm","Children under 8 years due to permanent tooth discoloration and enamel hypoplasia","Severe hepatic or renal impairment"]
| Precautions | ["Photosensitivity reactions","Esophageal ulceration if taken with insufficient fluids","Pseudotumor cerebri in adults","Pancreatitis","Hepatotoxicity","Renal impairment (accumulation may worsen renal function)","Superinfection with resistant organisms"] |
| Food/Dietary | Avoid dairy products (milk, cheese, yogurt) within 2-3 hours of taking Achromycin, as calcium binds tetracycline and reduces absorption. Also avoid iron-fortified foods, calcium-fortified juices, and high-calcium meals. Take on an empty stomach with a full glass of water; food, especially dairy, decreases absorption by up to 50%. |
Loading safety data…
| Fetal Monitoring | Monitor maternal liver function tests (AST, ALT, bilirubin) and renal function. Assess for signs of superinfection or pseudomembranous colitis. In prolonged therapy, monitor for bleeding (vitamin K deficiency). Fetal monitoring: Ultrasound for bone growth and development if prolonged second/third trimester exposure. |
| Fertility Effects | No known adverse effects on fertility in humans. Animal studies have shown no impairment of fertility. May cause transient decrease in sperm motility in vitro, but clinical significance is unclear. |
| Clinical Pearls | Achromycin (tetracycline) should be administered on an empty stomach (1 hour before or 2 hours after meals) to ensure adequate absorption. Avoid concurrent use with dairy products, antacids, iron, calcium, magnesium, or bismuth subsalicylate as they chelate tetracycline and reduce absorption. Tetracycline can cause photosensitivity; advise patients to avoid prolonged sun exposure and use sunscreen. It is contraindicated in pregnancy (risk of hepatotoxicity and fetal bone/teeth discoloration), lactation, and children under 8 years (permanent tooth discoloration and bone growth inhibition). Monitor for signs of superinfection, especially Clostridium difficile-associated diarrhea. Tetracycline may increase the effect of warfarin; monitor INR closely. |
| Patient Advice | Take this medication on an empty stomach, at least 1 hour before or 2 hours after meals. · Do not take with dairy products, antacids, iron supplements, or calcium supplements; separate by at least 2-3 hours. · Avoid excessive sunlight or tanning beds; use sunscreen and wear protective clothing to prevent severe sunburn. · Complete the full course of treatment even if you feel better; do not skip doses. · Notify your doctor immediately if you develop watery or bloody diarrhea, rash, headache, blurred vision, or signs of infection worsening. · Do not use if you are pregnant, planning to become pregnant, or breastfeeding; this medication can harm the unborn baby or nursing infant. · Keep out of reach of children; expired tetracycline can cause kidney damage. |