SUMYCIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for SUMYCIN (SUMYCIN).
Tetracycline antibiotic inhibiting bacterial protein synthesis by binding to the 30S ribosomal subunit, blocking aminoacyl-tRNA binding to the A site.
| Metabolism | Not extensively metabolized; primarily excreted unchanged in urine via glomerular filtration. |
| Excretion | Renal (60-80% unchanged via glomerular filtration), biliary/fecal (20-40%) |
| Half-life | 6-12 hours; prolonged in renal impairment (up to 24-48 hours in anuria) |
| Protein binding | 20-40%, primarily to albumin |
| Volume of Distribution | 1.5-2.0 L/kg; indicates extensive tissue distribution (e.g., lung, liver, bone) |
| Bioavailability | Oral: 30-50% (tetracycline base); higher for hydrochloride salt (60-80%) |
| Onset of Action | Oral: 1-2 hours; Intravenous: immediate |
| Duration of Action | 6-8 hours; longer with impaired renal function |
| Molecular Weight | 444.43 |
250-500 mg orally every 6 hours or 500 mg orally every 12 hours (maximum 2 g/day)
| Dosage form | TABLET |
| Renal impairment | CrCl 50-80 mL/min: 250 mg every 6 hours or 500 mg every 12 hours; CrCl 10-50 mL/min: 250 mg every 8-12 hours; CrCl <10 mL/min: 250 mg every 24 hours |
| Liver impairment | No dose adjustment required; however, use with caution in severe hepatic impairment due to potential hepatotoxicity. |
| Pediatric use | 25-50 mg/kg/day orally divided every 6 hours (maximum 2 g/day) |
| Geriatric use | No specific dose adjustment; monitor renal function and adjust dose based on creatinine clearance. |
| 1st trimester | Contraindicated due to risk of fetal harm; tetracyclines can cause retarded skeletal development and congenital anomalies. |
| 2nd trimester | Contraindicated due to risk of permanent tooth discoloration and enamel hypoplasia. |
| 3rd trimester | Contraindicated due to risk of permanent tooth discoloration and enamel hypoplasia. |
Clinical note
Comprehensive clinical and safety monograph for SUMYCIN (SUMYCIN).
| Placental transfer | Crosses placenta; achieves fetal serum concentrations approximately 50-60% of maternal levels. |
| Breastfeeding | Excreted into breast milk in low concentrations; potential for serious adverse reactions in nursing infants, including tooth discoloration and bone growth inhibition. Use is not recommended; alternative agents preferred. |
■ FDA Black Box Warning
Use during tooth development (last half of pregnancy, infancy, and childhood to 8 years) may cause permanent tooth discoloration and enamel hypoplasia; use during pregnancy may cause fetal harm; use in patients with renal impairment may lead to azotemia, hyperphosphatemia, and acidosis.
| Serious Effects |
Hypersensitivity to tetracyclinesPregnancyLactationChildren under 8 years of age (due to tooth discoloration and bone growth inhibition)
| Precautions | Photosensitivity reaction; superinfection with Clostridium difficile; hepatotoxicity; renal toxicity; use in pregnancy and children under 8 years; caution in renal impairment; may cause intracranial hypertension. |
| Food/Dietary | Avoid dairy products (milk, yogurt, cheese) and calcium-fortified foods within 2-3 hours of dosing. Also avoid iron-fortified foods and beverages (e.g., fortified cereals, spinach) near administration time. High-fat meals may delay absorption. No known restrictions with alcohol but may exacerbate GI upset. |
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| Lactation Rating |
| Avoid |
| Teratogenic Risk | Sumycin (tetracycline) is classified as FDA Pregnancy Category D. First trimester: Avoid due to possible teratogenic effects (limb anomalies, neural tube defects) based on animal data, but human data are limited. Second and third trimesters: Contraindicated due to risk of permanent tooth discoloration (yellow-gray-brown) and enamel hypoplasia in the fetus, and reversible inhibition of bone growth. Use after the 4th month of pregnancy is strongly discouraged. |
| Fetal Monitoring | Monitor maternal liver function, renal function, and blood counts. In pregnancy, serial ultrasound to assess fetal growth and development if exposure occurs during first trimester. For later exposure, monitor for signs of long bone growth inhibition and dental discoloration postnatally. |
| Fertility Effects | Tetracyclines have been associated with reversible impairment of fertility in animal studies, but human data on fertility effects are lacking. May affect spermatogenesis in males, but clinical significance is unknown. |
| Clinical Pearls | SUMYCIN (tetracycline) is bacteriostatic; avoid in children <8 years and pregnancy due to tooth discoloration and bone growth inhibition. Administer on empty stomach (1 hour before or 2 hours after meals) with full glass of water to reduce esophageal irritation. Avoid concurrent dairy, antacids, iron, calcium, magnesium, and zinc supplements. Monitor for photosensitivity; advise sun protection. May reduce effectiveness of oral contraceptives; recommend backup contraception. |
| Patient Advice | Take on an empty stomach, 1 hour before or 2 hours after meals, with a full glass of water. · Avoid dairy products, antacids, iron supplements, and calcium or magnesium-containing products within 2-3 hours of taking this medication. · Do not take this medication right before lying down; stay upright for at least 10 minutes after taking to prevent throat irritation. · Use sunscreen and protective clothing during sun exposure; avoid tanning beds as this drug increases sun sensitivity. · Finish the entire prescribed course even if you feel better; do not skip doses. · Tell your doctor if you are pregnant, planning to become pregnant, or breastfeeding; this medication may harm the baby. · If you take oral contraceptives, use an additional non-hormonal birth control method while on this medication. · Store at room temperature away from light and moisture; do not use after expiration date. |