ACCUTANE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ACCUTANE (ACCUTANE).
Retinoid that reduces sebum production, normalizes follicular keratinization, and decreases Propionibacterium acnes growth by binding to nuclear retinoic acid receptors, altering gene expression.
| Metabolism | Primarily metabolized in the liver by cytochrome P450 enzymes (CYP2C8, CYP3A4, and CYP2B6) into major metabolites: 4-oxo-isotretinoin (primary), tretinoin, and 4-oxo-tretinoin. Undergoes glucuronidation and excretion via urine and feces. |
| Excretion | Renal and biliary: approximately equal amounts of metabolites are excreted in urine and feces. Unchanged drug is not excreted. Major metabolites: 4-oxo-isotretinoin, tretinoin, 4-oxo-tretinoin. Renal excretion of metabolites accounts for ~65-83% of the dose; fecal excretion accounts for the remainder. |
| Half-life | Terminal elimination half-life of isotretinoin is 10-20 hours. The half-life of the major metabolite, 4-oxo-isotretinoin, is 11-50 hours. The long half-life of the metabolite may contribute to sustained clinical effects. |
| Protein binding | Isotretinoin is >99.9% bound to plasma proteins, primarily albumin. The active metabolite 4-oxo-isotretinoin is also highly protein bound (>99%). |
| Volume of Distribution | Apparent volume of distribution is approximately 89-175 L (not reported per kg, but typical Vd/F is 89-175 L). In a 70 kg individual, this corresponds to ~1.3-2.5 L/kg, indicating extensive tissue distribution. |
| Bioavailability | Oral bioavailability is approximately 25% due to extensive first-pass metabolism. Bioavailability is increased approximately 1.5- to 2-fold when taken with food (especially high-fat meal). |
| Onset of Action | Oral administration: Clinical improvement typically observed within 1-2 months of initiating therapy, with maximal effect by 4-5 months. No immediate onset; requires cumulative dosing. |
| Duration of Action | After a standard 16-20 week course, therapeutic effects (remission of acne) persist for months to years. However, retinoid levels decline rapidly after discontinuation; clinical effect outlasts drug presence. Repeat courses may be needed for relapse. |
Isotretinoin 0.5-1 mg/kg/day orally in 2 divided doses for 15-20 weeks.
| Dosage form | CAPSULE |
| Renal impairment | Contraindicated in severe renal impairment (GFR <30 mL/min); no dose adjustment recommended in mild-to-moderate impairment. |
| Liver impairment | Contraindicated in Child-Pugh class B or C; use with caution in class A (reduce dose by 50% and monitor). |
| Pediatric use | Approved for severe recalcitrant nodular acne in patients ≥12 years: 0.5-1 mg/kg/day in 2 divided doses; maximum 2 mg/kg/day. Cumulative dose 120-150 mg/kg. |
| Geriatric use | Not typically indicated in elderly; if used, start at lowest dose (0.5 mg/kg/day) and monitor for renal function and lipid abnormalities. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ACCUTANE (ACCUTANE).
| Breastfeeding | Isotretinoin is excreted in human breast milk. The milk-to-plasma ratio is approximately 0.2. Due to potential for serious adverse effects in the nursing infant, breastfeeding is contraindicated during therapy. |
| Teratogenic Risk | Isotretinoin is a known human teratogen. First trimester exposure results in a high risk (30-50%) of major fetal malformations including CNS abnormalities, facial dysmorphism, cardiovascular defects, and thymic hypoplasia. Second and third trimester exposure is associated with intellectual impairment and risk of premature epiphyseal closure. Contraindicated in pregnancy; must avoid conception during and for 1 month after therapy. |
■ FDA Black Box Warning
Isotretinoin must not be used by female patients who are or may become pregnant. There is an extremely high risk that severe birth defects will result if pregnancy occurs while taking isotretinoin in any amount, even for short periods. Additionally, isotretinoin is associated with serious psychiatric adverse events including suicide, suicide attempts, and depression.
| Serious Effects |
["Pregnancy or potential pregnancy (females of childbearing potential must use two forms of contraception)","Breastfeeding","Hypersensitivity to isotretinoin or any component of the formulation","Concomitant use with tetracycline antibiotics (increased risk of pseudotumor cerebri)"]
| Precautions | ["Pseudotumor cerebri (benign intracranial hypertension) - especially with concurrent tetracycline use","Pancreatitis: elevations in serum triglycerides and cholesterol; monitor lipids","Hepatotoxicity: monitor liver function tests","Inflammatory bowel disease: exacerbation of ulcerative colitis or Crohn's disease","Skeletal hyperostosis, premature epiphyseal closure, and decreased bone mineral density","Ocular effects: decreased night vision, corneal opacities, dry eyes","Hyperglycemia: risk of diabetes mellitus","Hearing impairment: tinnitus and hearing loss","Allergic reactions: severe anaphylaxis, vasculitis","Photosensitivity: use sunscreen and avoid UV light"] |
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| Fetal Monitoring | Pregnancy testing: Two negative pregnancy tests (one at baseline, one at day 5 of menstrual cycle or at least 11 days after last unprotected intercourse) required before initiation. Monthly pregnancy tests during therapy and one month after discontinuation. Use of two forms of effective contraception for at least 1 month before, during, and 1 month after therapy. Monitor for depression, suicidal ideation, and hepatic function. |
| Fertility Effects | Isotretinoin does not appear to impair fertility in males or females at therapeutic doses. However, due to teratogenicity, strict contraceptive measures are mandatory. Reversible alterations in menstrual cycle have been reported. |
| Food/Dietary | Take with a fatty meal (≥50g of fat) to enhance absorption. Avoid vitamin A supplements or high-dose multivitamins containing vitamin A to prevent toxicity. No specific food restrictions otherwise. |
| Clinical Pearls | ACCUTANE (isotretinoin) is a retinoid used for severe nodulocystic acne. It is highly teratogenic; require two negative pregnancy tests before initiation and monthly tests during therapy. Monitor liver enzymes and lipids monthly. Avoid concurrent tetracycline use due to increased risk of pseudotumor cerebri. Dry skin and cheilitis are expected; prophylactic moisturizers and lip balm are recommended. Screen for depression and suicidal ideation; report mood changes. Use with caution in patients with diabetes; may affect glycemic control. |
| Patient Advice | Must not become pregnant while taking this medication; use two effective birth control methods starting 1 month before, during, and 1 month after treatment. · Do not donate blood during therapy and for 1 month after stopping. · Avoid alcohol consumption; may increase risk of pancreatitis. · May cause severe dry skin, lips, eyes, and nose; use moisturizers and artificial tears as needed. · Report any vision changes, severe headache, or persistent nausea/vomiting immediately. · May cause temporary worsening of acne at start of treatment. · Avoid waxing, dermabrasion, or laser procedures during and for 6 months after therapy. · Take with food to improve absorption; swallow capsules whole. |