Tretinoin

12.1 Mechanism of Action Tretinoin induces cytodifferentiation and decreased proliferation of APL cells in culture and in vivo . In APL patients, tretinoin treatment produces an initial maturation of the primitive promyelocytes derived from the leukemic clone, followed by a repopulation of the bone marrow and peripheral blood by normal, polyclonal hematopoietic cells in patients achieving complete remission (CR). The exact mechanism of action of tretinoin in APL is unknown.

1 INDICATIONS AND USAGE Tretinoin capsules are indicated for the induction of remission in adults and pediatric patients 1 year of age and older with acute promyelocytic leukemia (APL) characterized by the presence of the t(15;17) translocation or PML/RARα gene expression, and who are refractory to or who have relapsed from anthracycline chemotherapy or for whom anthracycline-based chemotherapy is contraindicated. Tretinoin capsules are a retinoid indicated for induction of remission in adults and pediatric patients 1 year of age and older with acute promyelocytic leukemia (APL), characterized by presence of t(15;17) translocation or presence of PML/RARα gene expression, and who are refractory to or who have relapsed from anthracycline chemotherapy or for whom anthracycline-based chemotherapy is contraindicated.

2 DOSAGE AND ADMINISTRATION • The recommended dosage of tretinoin capsules is 22.5 mg/m 2 orally twice daily until complete remission. ( 2.2 ) • Discontinue 30 days after achievement of complete remission or after 90 days of treatment, whichever occurs first. ( 2.2 ) 2.1 Important Safety Information Verify pregnancy status in females of reproductive potential prior to initiating tretinoin capsules. Females of reproductive potential must have a negative pregnancy test before initiating tretinoin capsules [see Use in Specific Populations (8.3)] . 2.2 Recommended Dosage The recommended dosage of tretinoin capsules is 22.5 mg/m 2 orally twice daily until complete remission is documented. Discontinue tretinoin capsules 30 days after achievement of complete remission or after 90 days of treatment, whichever occurs first. Discontinue tretinoin capsules if the t(15;17) translocation or PML/RARα fusion has not been identified [see Warnings and Precautions (5.3)] . Take tretinoin capsules with a meal. Swallow tretinoin capsules whole with water. Do not chew, dissolve, or open capsule. Do not take a missed dose of tretinoin capsules unless it is more than 10 hours until the next scheduled dose. If vomiting occurs after tretinoin capsules administration, do not take an additional dose, but continue with the next scheduled dose.

6 ADVERSE REACTIONS The following clinically significant adverse reactions are described elsewhere in the labeling: • Differentiation Syndrome [see Warnings and Precautions ( 5.2 )] • Leukocytosis [see Warnings and Precautions ( 5.4 )] • Intracranial hypertension [see Warnings and Precautions (5.5)] • Lipid abnormalities [see Warnings and Precautions ( 5.6 )] • Hepatotoxicity [see Warnings and Precautions ( 5.7 )] • Thromboembolic events [see Warnings and Precautions (5 .8 )] The most common adverse reactions (≥30%) are headache, fever, skin/mucous membrane dryness, bone pain, malaise, shivering, upper respiratory tract disorders, dyspnea, hemorrhage, infections, nausea/vomiting, rash, peripheral edema, leukocytosis, pain, gastrointestinal hemorrhage, chest discomfort, abdominal pain ( 6.1 ). To report SUSPECTED ADVERSE REACTIONS, contact Endo at 1-800-828-9393 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Acute Promyelocytic Leukemia The safety of tretinoin capsules was evaluated in patients with APL who received tretinoin capsules at a dose of 22.5 mg/m 2 orally twice daily [see Clinical Studies ( 14 )] . The most common adverse reactions (≥30%) were headache, fever, skin/mucous membrane dryness, bone pain, malaise, shivering, upper respiratory tract disorders, dyspnea, hemorrhage, infections, nausea/vomiting, rash, peripheral edema, leukocytosis, pain, gastrointestinal hemorrhage, chest discomfort, abdominal pain. Table 1 summarizes the adverse reactions for patients with APL. Table 1. Adverse Reactions (≥ 10%) Occurring in Patients with APL Who Received Tretinoin Capsules Adverse Reaction Tretinoin Capsules All Grades (%) Nervous system disorders Headache 86 Dizziness 20 Paresthesias 17 Anxiety 17 Insomnia 14 Depression 14 Confusion 11 General disorders Fever 83 Skin/mucous membrane dryness 77 Malaise 66 Shivering 63 Peripheral edema 52 Pain 37 Chest discomfort 32 Edema 29 Mucositis 26 Weight increase 23 Anorexia 17 Weight decrease 17 Musculoskeletal and connective tissue disorders Bone pain 77 Myalgia 14 Respiratory, thoracic and mediastinal disorders Upper respiratory tract disorders 63 Dyspnea 60 Respiratory insufficiency 26 Pleural effusion 20 Rales 14 Expiratory wheezing 14 Pneumonia 14 Vascular disorders Hemorrhage 60 Gastrointestinal hemorrhage 34 Flushing 23 Hypotension 14 Hypertension 11 Phlebitis 11 Infections and infestations Infections 58 Gastrointestinal disorders Nausea/vomiting 57 Abdominal pain 31 Other gastrointestinal disorders 26 Diarrhea 23 Constipation 17 Dyspepsia 14 Abdominal distention 11 Skin and subcutaneous tissue disorders Rash 54 Pruritus 20 Increased sweating 20 Alopecia 14 Skin changes 14 Blood and lymphatic system disorders Leukocytosis 49 Differentiation syndrome 1 26 Disseminated intravascular coagulation 26 Ear and labyrinth disorders Earache or feeling of fullness in the ears 23 Cardiac disorders Arrhythmias 23 Eye disorders Visual disturbances 17 Ocular disorders 17 Renal and urinary disorders Renal insufficiency 11 1 Differentiation syndrome can be associated with other commonly reported events such as fever, leukocytosis, dyspnea, pneumonia, pleural effusion, pericardial effusion, hypotension, edema, weight gain, and renal failure. Adverse reactions that occurred in <10% of patients who received tretinoin capsules include: • Hepatobiliary disorders: Hepatosplenomegaly (9%), hepatitis (3%), unspecified liver disorder (3%). • Musculoskeletal and connective tissue disorders: Flank pain (9%), bone inflammation (3%). • Nervous system disorders: Agitation (9%), cerebral hemorrhage (9%), intracranial hypertension (9%), hallucination (6%), abnormal gait, agnosia, aphasia, asterixis, cerebellar edema, cerebellar disorders, convulsions, coma, CNS depression, dysarthria, encephalopathy, facial paralysis, hemiplegia, hyporeflexia, hypotaxia, no light reflex, neurologic reaction, spinal cord disorder, stroke, tremor, leg weakness, unconsciousness, dementia, forgetfulness, somnolence, and slow speech (3% each). • Renal and urinary disorders: Dysuria (9%), acute renal failure, micturition frequency, renal tubular necrosis, and enlarged prostate (3% each). • Respiratory, thoracic and mediastinal disorders: Lower respiratory tract disorders (9%), pulmonary infiltration (6%), bronchial asthma, pulmonary edema, larynx edema, and unspecified pulmonary disease (3% each). • Infections and infestations: Cellulitis (8%). • Blood and lymphatic system disorders: Lymph disorders (6%). • Cardiovascular disorders: Cardiac failure (6%), cardiac arrest, myocardial infarction, enlarged heart, heart murmur, myocarditis, pericarditis, and secondary cardiomyopathy (3% each). • Ear and labyrinth disorders:

7 DRUG INTERACTIONS • Strong CYP3A Inhibitors and Inducers: Avoid coadministration with strong CYP3A inhibitors and inducers. ( 7.1 ) • Concomitant Use of Products Known to Cause Intracranial Hypertension : Avoid concomitant use with other products that can cause intracranial hypertension. ( 7.2 ) • Vitamin A : Avoid concomitant use with vitamin A. ( 7.3 ) • Anti-fibrinolytic Agents : Avoid concomitant use with anti-fibrinolytic agents. ( 7.4 ) 7.1 Effects of Other Drugs on Tretinoin Capsules Strong or moderate CYP3A Inhibitors Avoid concomitant use of tretinoin capsules with strong CYP3A inhibitors if possible and monitor more frequently if concomitant use is unavoidable. Monitor patients taking moderate CYP3A inhibitors concomitantly with tretinoin capsules more frequently for adverse reactions. Tretinoin is a CYP3A substrate. Concomitant use with a strong CYP3A4 inhibitor increases tretinoin plasma concentrations, which may increase the risk of adverse reactions [see Clinical Pharmacology ( 12.3 )]. Strong CYP3A Inducers Concomitant use of tretinoin capsules with strong CYP3A4 inducers may decrease tretinoin plasma concentrations, which may reduce its efficacy. Avoid concomitant use with strong CYP3A inducers if possible. 7.2 Concomitant Use of Products Known to Cause Intracranial Hypertension Intracranial hypertension has been reported in patients who received tretinoin capsules and concomitant use of other products that can cause intracranial hypertension, such as tetracyclines, may increase the risk. Avoid concomitant use of tretinoin capsules with other products agents that can cause intracranial hypertension [see Warnings and Precautions ( 5.5 )] . 7.3 Vitamin A The concomitant use of vitamin A with tretinoin capsules may lead to vitamin A related adverse reactions. Avoid concomitant use of tretinoin capsules with vitamin A. 7.4 Anti-fibrinolytic Agents Fatal thrombotic complications have been reported in patients who have received tretinoin capsules and concomitant use of anti-fibrinolytic agents may increase the risk. Avoid concomitant use of tretinoin capsules with anti-fibrinolytic agents [see Warnings and Precautions ( 5.8 )].