Isotretinoin

INDICATIONS AND USAGE Isotretinoin capsules are indicated for the treatment of severe recalcitrant nodular acne in non-pregnant patients 12 years of age and older with multiple inflammatory nodules with a diameter of 5 mm or greater. Because of significant adverse reactions associated with its use, isotretinoin capsules are reserved for patients with severe nodular acne who are unresponsive to conventional therapy, including systemic antibiotics. Limitations of Use: If a second course of isotretinoin capsules therapy is needed, it is not recommended before a two month waiting period because the patient's acne may continue to improve following a 15 week to 20 week course of therapy [see Dosage and Administration ( 2.2 )]. Isotretinoin capsules are retinoids indicated for the treatment of severe recalcitrant nodular acne in non-pregnant patients 12 years of age and older with multiple inflammatory nodules with a diameter of 5 mm or greater. Because of significant adverse reactions associated with its use, isotretinoin capsules are reserved for patients with severe nodular acne who are unresponsive to conventional therapy, including systemic antibiotics. ( 1 ) Limitations of Use: If a second course of isotretinoin capsules therapy is needed, it is not recommended before a two month waiting period because the patient's acne may continue to improve following a 15 week to 20 week course of therapy. ( 1 )

DOSAGE AND ADMINISTRATION • ABSORICA is not substitutable with ABSORICA LD because of different bioavailability and recommended dosage. ( 2.1 , 5.3 ) • Recommended dosage for: o ABSORICA is 0.5 to 1 mg/kg/day given in two divided doses without regard to meals for 15 to 20 weeks ( 2.1 ) o ABSORICA LD is 0.4 to 0.8 mg/kg/day given in two divided doses without regard to meals for 15 to 20 weeks ( 2.1 ) • Adult patients with very severe disease (scarring, trunk involvement) may increase dosage to 2 mg/kg/day of ABSORICA (1.6 mg/kg/day of ABSORICA LD) in divided doses. ( 2.1 ) • Once daily dosing is not recommended. ( 2.1 ) • If a dose of ABSORICA/ABSORICA LD is missed, just skip that dose. Do not take two doses of ABSORICA/ABSORICA LD at the same time. ( 2.1 ) • Perform pregnancy tests prior to prescribing, each month during therapy, end of therapy, and one month after discontinuation. ( 2.3 , 8.3 ) • Prior to prescribing, perform fasting lipid profile and liver function tests. ( 2.3 ) 2.1 Recommended Dosage ABSORICA is not substitutable with ABSORICA LD [see Warnings and Precautions (5.3) ] . The recommended dosage of: • ABSORICA is 0.5 to 1 mg/kg/day given in two divided doses with or without meals for 15 to 20 weeks (see Table 1). • ABSORICA LD is 0.4 to 0.8 mg/kg/day given in two divided doses with or without meals for 15 to 20 weeks (see Table 2). To decrease the risk of esophageal irritation, instruct patients to swallow the capsules with a full glass of liquid. During treatment, the dosage may be adjusted according to response of the disease and/or adverse reactions, some of which may be dose-related. Adult patients whose disease is very severe with scarring or is primarily manifested on the trunk may require dosage adjustments up to 2 mg/kg/day for ABSORICA (1.6 mg/kg/day for ABSORICA LD) in divided doses, as tolerated. The safety and effectiveness of once daily dosing with ABSORICA/ABSORICA LD has not been established and is not recommended. If a dose of ABSORICA/ABSORICA LD is missed, just skip that dose. Do not take two doses of ABSORICA/ ABSORICA LD at the same time. Table 1: ABSORICA Daily Dosage by Body Weight 1 Body Weight Total Daily Dosage (mg) 1 0.5 mg/kg 1 mg/kg 2 mg/kg 40 kg 20 40 80 50 kg 25 50 100 60 kg 30 60 120 70 kg 35 70 140 80 kg 40 80 160 90 kg 45 90 180 100 kg 50 100 200 1 Administer in two divided doses with or without meals Table 2: ABSORICA LD Daily Dosage by Body Weight 1 Body Weight Total Daily Dosage (mg) 1 0.4 mg/kg 0.8 mg/kg 1.6 mg/kg 40 kg 16 32 64 50 kg 20 40 80 60 kg 24 48 96 70 kg 28 56 112 80 kg 32 64 128 90 kg 36 72 144 100 kg 40 80 160 1 Administer in two divided doses with or without meals 2.2 Duration of Use A normal course of treatment is 15 to 20 weeks. If the total nodule count has been reduced by more than 70% prior to completing 15 to 20 weeks of treatment, may discontinue ABSORICA/ABSORICA LD. After a period of 2 months or more off therapy, and if warranted by persistent or recurring severe nodular acne, may initiate a second course of ABSORICA/ABSORICA LD in patients who have completed skeletal growth. The use of another course of ABSORICA/ABSORICA LD therapy is not recommended before a two-month waiting period because the patient’s acne may continue to improve after a 15 to 20-week course of therapy. The optimal interval before retreatment has not been defined for patients who have not completed skeletal growth. Long-term use of ABSORICA/ABSORICA LD, even in low dosages, has not been studied, and is not recommended. The effect of long-term use of ABSORICA/ABSORICA LD on bone loss is unknown [see Warnings and Precautions (5.12) ] . 2.3 Laboratory Testing Prior to Administration The following laboratory testing must be completed prior to ABSORICA/ABSORICA LD use: • Pregnancy testing: Ensure patient is not pregnant prior to administering ABSORICA/ABSORICA LD [see Contraindications (4) and Use in Specific Populations (8.1 , 8.3) ] • A fasting lipid profile including triglycerides [see Warnings and Precautions (5.8 , 5.15) ] . • Liver function tests [see Warnings and Precautions (5.10 , 5.15) ] .

WARNINGS Psychiatric Disorders Isotretinoin capsules may cause depression, psychosis and, rarely, suicidal ideation, suicide attempts, suicide, and aggressive and/or violent behaviors. No mechanism of action has been established for these events (see ADVERSE REACTIONS: Psychiatric ). Prescribers should read the brochure, Recognizing Psychiatric Disorders in Adolescents and Young Adults: A Guide for Prescribers of Isotretinoin. Prescribers should be alert to the warning signs of psychiatric disorders to guide patients to receive the help they need. Therefore, prior to initiation of isotretinoin capsules therapy, patients and family members should be asked about any history of psychiatric disorder, and at each visit during therapy patients should be assessed for symptoms of depression, mood disturbance, psychosis, or aggression to determine if further evaluation may be necessary. Signs and symptoms of depression, as described in the brochure ("Recognizing Psychiatric Disorders in Adolescents and Young Adults"), include sad mood, hopelessness, feelings of guilt, worthlessness or helplessness, loss of pleasure or interest in activities, fatigue, difficulty concentrating, change in sleep pattern, change in weight or appetite, suicidal thoughts or attempts, restlessness, irritability, acting on dangerous impulses, and persistent physical symptoms unresponsive to treatment. Patients should stop isotretinoin capsules and the patient or a family member should promptly contact their prescriber if the patient develops depression, mood disturbance, psychosis, or aggression, without waiting until the next visit. Discontinuation of isotretinoin capsules therapy may be insufficient; further evaluation may be necessary. While such monitoring may be helpful, it may not detect all patients at risk. Patients may report mental health problems or family history of psychiatric disorders. These reports should be discussed with the patient and/or the patient's family. A referral to a mental health professional may be necessary. The physician should consider whether isotretinoin capsules therapy is appropriate in this setting; for some patients the risks may outweigh the benefits of isotretinoin capsules therapy. Pseudotumor Cerebri Isotretinoin capsules use has been associated with a number of cases of pseudotumor cerebri (benign intracranial hypertension), some of which involved concomitant use of tetracyclines. Concomitant treatment with tetracyclines should therefore be avoided. Early signs and symptoms of pseudotumor cerebri include papilledema, headache, nausea and vomiting, and visual disturbances. Patients with these symptoms should be screened for papilledema and, if present, they should be told to discontinue isotretinoin capsules immediately and be referred to a neurologist for further diagnosis and care (see ADVERSE REACTIONS: Neurological ). Serious Skin Reactions There have been post-marketing reports of erythema multiforme and severe skin reactions [e.g., Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN)] associated with isotretinoin use. These events may be serious and result in death, life-threatening events, hospitalization, or disability. Patients should be monitored closely for severe skin reactions, and discontinuation of isotretinoin capsules should be considered if warranted. Pancreatitis Acute pancreatitis has been reported in patients with either elevated or normal serum triglyceride levels. In rare instances, fatal hemorrhagic pancreatitis has been reported. Isotretinoin capsules should be stopped if hypertriglyceridemia cannot be controlled at an acceptable level or if symptoms of pancreatitis occur. Lipids Elevations of serum triglycerides in excess of 800 mg/dL have been reported in patients treated with isotretinoin capsules. Marked elevations of serum triglycerides were reported in approximately 25% of patients receiving isotretinoin capsules in clinical trials. In addition, approximately 15% developed a decrease in high-density lipoproteins and about 7% showed an increase in cholesterol levels. In clinical trials, the effects on triglycerides, HDL, and cholesterol were reversible upon cessation of isotretinoin capsules therapy. Some patients have been able to reverse triglyceride elevation by reduction in weight, restriction of dietary fat and alcohol, and reduction in dose while continuing isotretinoin capsules. 5 Blood lipid determinations should be performed before isotretinoin capsules are given and then at intervals until the lipid response to isotretinoin capsules is established, which usually occurs within 4 weeks. Especially careful consideration must be given to risk/benefit for patients who may be at high risk during isotretinoin capsules therapy (patients with diabetes, obesity, increased alcohol intake, lipid metabolism disorder or familial history of lipid metabolism disorder). If isotretinoin capsules therapy is instituted, more frequent checks of serum values for lipids and/or blood sugar are recommended (see PRECAUTIONS: Laboratory Tests ). The cardiovascular consequences of hypertriglyceridemia associated with isotretinoin capsules are unknown. Animal Studies In rats given 8 or 32 mg/kg/day of isotretinoin (1.3 to 5.3 times the recommended clinical dose of 1 mg/kg/day after normalization for total body surface area) for 18 months or longer, the incidences of focal calcification, fibrosis and inflammation of the myocardium, calcification of coronary, pulmonary and mesenteric arteries, and metastatic calcification of the gastric mucosa were greater than in control rats of similar age. Focal endocardial and myocardial calcifications associated with calcification of the coronary arteries were observed in two dogs after approximately 6 to 7 months of treatment with isotretinoin at a dosage of 60 to 120 mg/kg/day (30 to 60 times the recommended clinical dose of 1 mg/kg/day, respectively, after normalization for total body surface area). Hearing Impairment Impaired hearing has been reported in patients taking isotretinoin capsules; in some cases, the hearing impairment has been reported to persist after therapy has been discontinued. Mechanism(s) and causality for this event have not been established. Patients who experience tinnitus or hearing impairment should discontinue isotretinoin capsules treatment and be referred for specialized care for further evaluation (see ADVERSE REACTIONS: Special Senses ). Hepatotoxicity Clinical hepatitis considered to be possibly or probably related to isotretinoin capsules therapy has been reported. Additionally, mild to moderate elevations of liver enzymes have been observed in approximately 15% of individuals treated during clinical trials, some of which normalized with dosage reduction or continued administration of the drug. If normalization does not readily occur or if hepatitis is suspected during treatment with isotretinoin capsules, the drug should be discontinued and the etiology further investigated. Inflammatory Bowel Disease Isotretinoin capsules have been associated with inflammatory bowel disease (including regional ileitis) in patients without a prior history of intestinal disorders. In some instances, symptoms have been reported to persist after isotretinoin capsules treatment has been stopped. Patients experiencing abdominal pain, rectal bleeding or severe diarrhea should discontinue isotretinoin capsules immediately (see ADVERSE REACTIONS: Gastrointestinal ). Skeletal Bone Mineral Density Effects of multiple courses of isotretinoin capsules on the developing musculoskeletal system are unknown. There is some evidence that long-term, high-dose, or multiple courses of therapy with isotretinoin have more of an effect than a single course of therapy on the musculoskeletal system. In an open-label clinical trial (N=217) of a single course of therapy with isotretinoin capsules for severe recalcitrant nodular acne, bone density measurements at several skeletal sites were

CONTRAINDICATIONS Pregnancy ( 4.1 , 8.1 ) Hypersensitivity to this product or any of its components ( 4.2 , 5.15 ) 4.1 Pregnancy Isotretinoin capsules are contraindicated in pregnancy [see Warnings and Precautions (5.1) and Use in Specific Populations (8.1) ] . 4.2 Hypersensitivity Isotretinoin capsules are contraindicated in patients with hypersensitivity to isotretinoin (or Vitamin A, given the chemical similarity to isotretinoin) or to any of its components (anaphylaxis and other allergic reactions have occurred) [see Warnings and Precautions (5.14) ] .

Drug Interactions Vitamin A: Because of the relationship of isotretinoin capsules to vitamin A, patients should be advised against taking vitamin supplements containing vitamin A to avoid additive toxic effects. Tetracyclines: Concomitant treatment with isotretinoin capsules and tetracyclines should be avoided because isotretinoin capsules use has been associated with a number of cases of pseudotumor cerebri (benign intracranial hypertension), some of which involved concomitant use of tetracyclines. Micro-dosed Progesterone Preparations: Micro-dosed progesterone preparations ("minipills" that do not contain an estrogen) may be an inadequate method of contraception during isotretinoin capsules therapy. Although other hormonal contraceptives are highly effective, there have been reports of pregnancy from patients who can become pregnant who have used combined oral contraceptives, as well as transdermal patch/injectable/implantable/vaginal ring hormonal birth control products. These reports are more frequent for patients who can become pregnant who use only a single form of contraception. It is not known if hormonal contraceptives differ in their effectiveness when used with isotretinoin capsules. Therefore, it is critically important for patients who can become pregnant to select and commit to use two forms of effective contraception simultaneously, at least one of which must be a primary form (see PRECAUTIONS ). Norethindrone/ethinyl estradiol: In a study of 31 premenopausal female patients with severe recalcitrant nodular acne receiving OrthoNovum ® 7/7/7 Tablets as an oral contraceptive agent, isotretinoin capsules at the recommended dose of 1 mg/kg/day, did not induce clinically relevant changes in the pharmacokinetics of ethinyl estradiol and norethindrone and in the serum levels of progesterone, follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Prescribers are advised to consult the package insert of medication administered concomitantly with hormonal contraceptives, since some medications may decrease the effectiveness of these birth control products. St. John's Wort: Isotretinoin capsules use is associated with depression in some patients (see WARNINGS: Psychiatric Disorders and ADVERSE REACTIONS: Psychiatric ). Patients should be prospectively cautioned not to self-medicate with the herbal supplement St. John's Wort because a possible interaction has been suggested with hormonal contraceptives based on reports of breakthrough bleeding on oral contraceptives shortly after starting St. John's Wort. Pregnancies have been reported by users of combined hormonal contraceptives who also used some form of St. John's Wort. Phenytoin : Isotretinoin capsules have not been shown to alter the pharmacokinetics of phenytoin in a study in seven healthy volunteers. These results are consistent with the in vitro finding that neither isotretinoin nor its metabolites induce or inhibit the activity of the CYP 2C9 human hepatic P450 enzyme. Phenytoin is known to cause osteomalacia. No formal clinical studies have been conducted to assess if there is an interactive effect on bone loss between phenytoin and isotretinoin capsules. Therefore, caution should be exercised when using these drugs together. Systemic Corticosteroids: Systemic corticosteroids are known to cause osteoporosis. No formal clinical studies have been conducted to assess if there is an interactive effect on bone loss between systemic corticosteroids and isotretinoin capsules. Therefore, caution should be exercised when using these drugs together.

ADVERSE REACTIONS The following adverse reactions with ABSORICA/ABSORICA LD or other isotretinoin capsule products are described in more detail in other sections of the labeling: • Embryo-Fetal Toxicity [see Warnings and Precautions ( 5.1 )] • Psychiatric Disorders [see Warnings and Precautions ( 5.4 )] • Intracranial Hypertension (Pseudotumor Cerebri) [see Warnings and Precautions ( 5.5 )] • Serious Skin Reactions [see Warnings and Precautions ( 5.6 )] • Pancreatitis [see Warnings and Precautions ( 5.7 )] • Lipid Abnormalities [see Warnings and Precautions ( 5.8 )] • Hearing Impairment [see Warnings and Precautions ( 5.9 )] • Hepatotoxicity [see Warnings and Precautions ( 5.10 )] • Inflammatory Bowel Disease [see Warnings and Precautions ( 5.11 )] • Musculoskeletal Abnormalities [see Warnings and Precautions ( 5.12 )] • Ocular Abnormalities [see Warnings and Precautions ( 5.13 )] • Hypersensitivity Reactions [see Warnings and Precautions ( 5.14 )] The following adverse reactions associated with the use of isotretinoin capsules were identified in clinical studies or postmarketing reports. Because some of these reactions were reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Dose Relationship Cheilitis and hypertriglyceridemia were dose related. Body as a Whole Fatigue, irritability, pain, allergic reactions, systemic hypersensitivity, edema, lymphadenopathy, weight loss. Cardiovascular Vascular thrombotic disease, stroke, palpitation, tachycardia. Endocrine/Metabolism and Nutritional Decreased appetite, weight fluctuation, alterations in blood sugar. Gastrointestinal Dry lips, chapped lips, cheilitis, nausea, constipation, diarrhea, abdominal pain, vomiting, inflammatory bowel disease, hepatitis, pancreatitis, bleeding and inflammation of the gums, colitis, esophagitis, esophageal ulceration, ileitis. Hematologic Anemia and decreased RBC parameters, thrombocytopenia, increased platelet counts, decreased WBC counts, severe neutropenia, rare reports of agranulocytosis. Infections and Infestations Nasopharyngitis, hordeolum, infections (including disseminated herpes simplex and upper respiratory tract infection). Laboratory Abnormalities The following lab tests were increased: creatine phosphokinase (CPK), triglycerides, alanine aminotransferase (SGPT), aspartate aminotransferase (SGOT), gamma-glutamyltransferase (GGTP), cholesterol, low density lipoprotein (LDL), alkaline phosphatase, bilirubin, LDH, fasting blood glucose, uric acid, and sedimentation rate. However, high density lipoprotein (HDL) was decreased. Urine findings included increased white cells, proteinuria, microscopic or gross hematuria. Musculoskeletal and Connective Tissue Decreases in bone mineral density, musculoskeletal symptoms (sometimes severe) including back pain, arthralgia, musculoskeletal pain, neck pain, extremity pain, myalgia, musculoskeletal stiffness [see Warnings and Precautions (5.12)] , skeletal hyperostosis, calcification of tendons and ligaments, premature epiphyseal closure, tendonitis, arthritis, transient chest pain, and rare reports of rhabdomyolysis. Neurological Headache, syncope, intracranial hypertension (pseudotumor cerebri), dizziness, drowsiness, lethargy, malaise, nervousness, paresthesia, seizures, stroke, weakness. Psychiatric Suicidal ideation, insomnia, anxiety, depression, irritability, panic attack, anger, euphoria, violent behaviors, emotional instability, suicide attempts, suicide, aggression, psychosis and auditory hallucinations. Of the patients reporting depression, some reported that the depression subsided with discontinuation of therapy and recurred with reinstitution of therapy. Reproductive System Abnormal menses, sexual dysfunction, including erectile dysfunction, decreased libido, decreased vaginal lubrication, and vaginal dryness. Respiratory Epistaxis, nasal dryness, bronchospasm (with or without a history of asthma), respiratory infection, voice alteration. Skin and Subcutaneous Tissue Dry skin, dermatitis, eczema, rash, contact dermatitis, alopecia, pruritus, sunburn, erythema, acne fulminans, alopecia(which in some cases persisted), bruising, dry nose, eruptive xanthomas, erythema multiforme, flushing, skin fragility, hair abnormalities, hirsutism, hyperpigmentation and hypopigmentation, nail dystrophy, paronychia, peeling of palms and soles, photoallergic/photosensitizing reactions, pruritus, pyogenic granuloma, rash (including facial erythema, seborrhea, and eczema), Stevens-Johnson syndrome, increased sunburn susceptibility, sweating, toxic epidermal necrolysis, urticaria,vasculitis (including granulomatosis with polyangiitis), abnormal wound healing (delayed healing or exuberant granulation tissue with crusting). Senses Hearing: tinnitus and hearing impairment. Ocular : dry eyes, reduced visual acuity, blurred vision, eye pruritis, eye irritation, asthenopia, decreased night vision, ocular hyperemia, increased lacrimation, conjunctivitis, corneal opacities, decreased night vision which may persist, cataracts, color vision disorder, conjunctivitis, eyelid inflammation, keratitis, optic neuritis, photobia, visual disturbances. Renal and Urinary Glomerulonephritis. Most common adverse reactions (incidence ≥5%) are: dry lips, dry skin, back pain, dry eye, arthralgia, epistaxis, headache, nasopharyngitis, chapped lips, dermatitis, increased creatine kinase, cheilitis, musculoskeletal discomfort, upper respiratory tract infection, reduced visual acuity. (6) To report SUSPECTED ADVERSE REACTIONS, contact Sun Pharmaceutical Industries, Inc. at 1-800-818-4555 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch or iPLEDGE at (1-866-495-0654).

CLINICAL PHARMACOLOGY Isotretinoin is a retinoid, which when administered in pharmacologic dosages of 0.5 to 1 mg/kg/day (see DOSAGE AND ADMINISTRATION ), inhibits sebaceous gland function and keratinization. The exact mechanism of action of isotretinoin is unknown. Nodular Acne Clinical improvement in nodular acne patients occurs in association with a reduction in sebum secretion. The decrease in sebum secretion is temporary and is related to the dose and duration of treatment with isotretinoin capsules, and reflects a reduction in sebaceous gland size and an inhibition of sebaceous gland differentiation. 1 Pharmacokinetics Absorption Due to its high lipophilicity, oral absorption of isotretinoin is enhanced when given with a high fat meal. In a crossover study, 74 healthy adult subjects received a single 80 mg oral dose (2 x 40 mg capsules) of isotretinoin capsules under fasted and fed conditions. Both peak plasma concentration (C max ) and the total exposure (AUC) of isotretinoin were more than doubled following a standardized high fat meal when compared with isotretinoin capsules given under fasted conditions (see Table 2 ). The observed elimination half-life was unchanged. This lack of change in half-life suggests that food increases the bioavailability of isotretinoin without altering its disposition. The time to peak concentration (T max ) was also increased with food and may be related to a longer absorption phase. Therefore, isotretinoin capsules should always be taken with food (see DOSAGE AND ADMINISTRATION ). Clinical studies have shown that there is no difference in the pharmacokinetics of isotretinoin between patients with nodular acne and healthy subjects with normal skin. Table 2 Pharmacokinetic Parameters of Isotretinoin Mean (%CV), N = 74 * Eating a standardized high fat meal Isotretinoin Capsules 2 x 40 mg Capsules AUC o-∞ (ng • hr/mL) C max (ng/mL) T max (hr) t ½ (hr) Fed * 10,004 (22%) 862 (22%) 5.3 (77%) 21 (39%) Fasted 3,703 (46%) 301 (63%) 3.2 (56%) 21 (30%) Distribution Isotretinoin is more than 99.9% bound to plasma proteins, primarily albumin. Metabolism Following oral administration of isotretinoin, at least three metabolites have been identified in human plasma: 4- oxo -isotretinoin, retinoic acid (tretinoin), and 4- oxo -retinoic acid (4- oxo -tretinoin). Retinoic acid and 13- cis -retinoic acid are geometric isomers and show reversible interconversion. The administration of one isomer will give rise to the other. Isotretinoin is also irreversibly oxidized to 4- oxo -isotretinoin, which forms its geometric isomer 4- oxo -tretinoin. After a single 80 mg oral dose of isotretinoin to 74 healthy adult subjects, concurrent administration of food increased the extent of formation of all metabolites in plasma when compared to the extent of formation under fasted conditions. All of these metabolites possess retinoid activity that is in some in vitro models more than that of the parent isotretinoin. However, the clinical significance of these models is unknown. After multiple oral dose administration of isotretinoin to adult cystic acne patients (≥18 years), the exposure of patients to 4- oxo -isotretinoin at steady-state under fasted and fed conditions was approximately 3.4 times higher than that of isotretinoin. In vitro studies indicate that the primary P450 isoforms involved in isotretinoin metabolism are 2C8, 2C9, 3A4, and 2B6. Isotretinoin and its metabolites are further metabolized into conjugates, which are then excreted in urine and feces. Elimination Following oral administration of an 80 mg dose of 14 C-isotretinoin as a liquid suspension, 14 C-activity in blood declined with a half-life of 90 hours. The metabolites of isotretinoin and any conjugates are ultimately excreted in the feces and urine in relatively equal amounts (total of 65% to 83%). After a single 80 mg oral dose of isotretinoin to 74 healthy adult subjects under fed conditions, the mean ± SD elimination half-lives (t ½ ) of isotretinoin and 4- oxo -isotretinoin were 21 ± 8.2 hours and 24 ± 5.3 hours, respectively. After both single and multiple doses, the observed accumulation ratios of isotretinoin ranged from 0.9 to 5.43 in patients with cystic acne. Special Patient Populations Pediatric Patients The pharmacokinetics of isotretinoin were evaluated after single and multiple doses in 38 pediatric patients (12 to 15 years) and 19 adult patients (≥ 18 years) who received isotretinoin for the treatment of severe recalcitrant nodular acne. In both age groups, 4- oxo -isotretinoin was the major metabolite; tretinoin and 4- oxo -tretinoin were also observed. The dose-normalized pharmacokinetic parameters for isotretinoin following single and multiple doses are summarized in Table 3 for pediatric patients. There were no statistically significant differences in the pharmacokinetics of isotretinoin between pediatric and adult patients. Table 3 Pharmacokinetic Parameters of Isotretinoin Following Single and Multiple Dose Administration in Pediatric Patients, 12 to 15 Years of Age Mean (± SD), N = 38 * *The single and multiple dose data in this table were obtained following a non-standardized meal that is not comparable to the high fat meal that was used in the study in Table 2. † Median (range) Parameter Isotretinoin (Single Dose) Isotretinoin (Steady-State) C max (ng/mL) 573.25 (278.79) 731.98 (361.86) AUC (0 to 12) (ng·hr/mL) 3,033.37 (1,394.17) 5,082 (2,184.23) AUC (0 to 24) (ng·hr/mL) 6,003.81 (2,885.67) -- T max (hr) † 6 (1 to 24.6) 4 (0 to 12) C SSmin (ng/mL) -- 352.32 (184.44) T ½ (hr) -- 15.69 (5.12) CL/F (L/hr) -- 17.96 (6.27) In pediatric patients (12 to 15 years), the mean ± SD elimination half-lives (t ½ ) of isotretinoin and 4-oxo-isotretinoin were 15.7 ± 5.1 hours and 23.1 ± 5.7 hours, respectively. The accumulation ratios of isotretinoin ranged from 0.46 to 3.65 for pediatric patients.