Vesanoid

VESANOID (tretinoin) is supplied as 10 mg capsules, two-tone (lengthwise), orange-yellow and reddish-brown and imprinted VESANOID (tretinoin) 10 ROCHE. Supplied in high-density polyethylene, opaque bottles of 100 capsules with child-resistant closure (NDC 0004-0250-01).

Store at 15° to 30°C (59° to 86°F). Protect from light.

Distributed by: Pharmaceuticals Roche Laboratories Inc. 340 kingsland street, Nutley, New Jersey 07110- 1199. Revised: July 2008. FDA Rev date: 7/1/2008

VESANOID (tretinoin) capsules are indicated for the induction of remission in patients with acute promyelocytic leukemia (APL), French-American-British (FAB) classification M3 (including the M3 variant), characterized by the presence of the t(15;17) translocation and/or the presence of the PML/RARα gene who are refractory to, or who have relapsed from, anthracycline chemotherapy, or for whom anthracycline-based chemotherapy is contraindicated. VESANOID (tretinoin) is for the induction of remission only. The optimal consolidation or maintenance regimens have not been defined, but all patients should receive an accepted form of remission consolidation and/or maintenance therapy for APL after completion of induction therapy with VESANOID (tretinoin).

The recommended dose is 45 mg/m²/day administered as two evenly divided doses until complete remission is documented. Therapy should be discontinued 30 days after achievement of complete remission or after 90 days of treatment, whichever occurs first.

If after initiation of treatment of VESANOID (tretinoin) the presence of the t(15;17) translocation is not confirmed by cytogenetics and/or by polymerase chain reaction studies and the patient has not responded to VESANOID (tretinoin) , alternative therapy appropriate for acute myelogenous leukemia should be considered.

VESANOID (tretinoin) is for the induction of remission only. Optimal consolidation or maintenance regimens have not been determined. All patients should, therefore, receive a standard consolidation and/or maintenance chemotherapy regimen for APL after induction therapy with VESANOID (tretinoin) , unless otherwise contraindicated.

VESANOID (tretinoin) is contraindicated in patients with a known hypersensitivity to VESANOID (tretinoin) , any of its components, or other retinoids. VESANOID (tretinoin) should not be given to patients who are sensitive to parabens, which are used as preservatives in the gelatin capsule.

WARNINGS

Pregnancy Category D - See Boxed WARNINGS

Tretinoin has teratogenic and embryotoxic effects in mice, rats, hamsters, rabbits and pigtail monkeys, and may be expected to cause fetal harm when administered to a pregnant woman. Tretinoin causes fetal resorptions and a decrease in live fetuses in all animals studied. Gross external, soft tissue and skeletal alterations occurred at doses higher than 0.7 mg/kg/day in mice, 2 mg/kg/day in rats, 7 mg/kg/day in hamsters, and at a dose of 10 mg/kg/day, the only dose tested, in pigtail monkeys (about 1/20, 1/4, and 1/2 and 4 times the human dose, respectively, on a mg/m² basis).

There are no adequate and well-controlled studies in pregnant women. Although experience with humans administered VESANOID (tretinoin) is extremely limited, increased spontaneous abortions and major human fetal abnormalities related to the use of other retinoids have been documented in humans. Reported defects include abnormalities of the CNS, musculoskeletal system, external ear, eye, thymus and great vessels; and facial dysmorphia, cleft palate, and parathyroid hormone deficiency. Some of these abnormalities were fatal. Cases of IQ scores less than 85, with or without obvious CNS abnormalities, have also been reported. All fetuses exposed during pregnancy can be affected and at the present time there is no antepartum means of determining which fetuses are and are not affected.

Effective contraception must be used by all females during VESANOID (tretinoin) therapy and for 1 month following discontinuation of therapy. Contraception must be used even when there is a history of infertility or menopause, unless a hysterectomy has been performed. Whenever contraception is required, it is recommended that two reliable forms of contraception be used simultaneously, unless abstinence is the chosen method. If pregnancy does occur during treatment, the physician and patient should discuss the desirability of continuing or terminating the pregnancy.

Patients Without the t(15;17) Translocation

Initiation of therapy with VESANOID (tretinoin) may be based on the morphological diagnosis of acute promyelocytic leukemia. Confirmation of the diagnosis of APL should be sought by detection of the t(15;17) genetic marker by cytogenetic studies. If these are negative, PML/RARα fusion should be sought using molecular diagnostic techniques. The response rate of other AML subtypes to VESANOID (tretinoin) has not been demonstrated; therefore, patients who lack the genetic marker should be considered for alternative treatment.

Retinoic Acid-APL (RA-APL) Syndrome

In up to 25% of patients with APL treated with VESANOID (tretinoin) , a syndrome occurs which can be fatal (see boxed WARNINGS and ADVERSE REACTIONS).

Leukocytosis at Presentation and Rapidly Evolving Leukocytosis During VESANOID Treatment

See boxed WARNINGS.

Pseudotumor Cerebri

Retinoids, including VESANOID (tretinoin) , have been associated with pseudotumor cerebri (benign intracranial hypertension), especially in pediatric patients. The concomitant use of other agents known to cause pseudotumor cerebri/intracranial hypertension, such as tetracyclines, might increase the risk of this condition (see PRECAUTIONS: DRUG INTERACTIONS). Early signs and symptoms of pseudotumor cerebri include papilledema, headache, nausea and vomiting, and visual disturbances. Patients with these symptoms should be evaluated for pseudotumor cerebri, and, if present, appropriate care should be instituted in concert with neurological assessment.

Lipids

Up to 60% of patients experienced hypercholesterolemia and/or hypertriglyceridemia, which were reversible upon completion of treatment. The clinical consequences of temporary elevation of triglycerides and cholesterol are unknown, but venous thrombosis and myocardial infarction have been reported in patients who ordinarily are at low risk for such complications.

Elevated Liver Function Test Results

Elevated liver function test results occur in 50% to 60% of patients during treatment. Liver function test results should be carefully monitored during treatment and consideration be given to a temporary withdrawal of VESANOID (tretinoin) if test results reach >5 times the upper limit of normal values. However, the majority of these abnormalities resolve without interruption of VESANOID (tretinoin) or after completion of treatment.

PRECAUTIONS

General

VESANOID (tretinoin) has potentially significant toxic side effects in APL patients. Patients undergoing therapy should be closely observed for signs of respiratory compromise and/or leukocytosis (see boxed WARNINGS). Supportive care appropriate for APL patients, eg, prophylaxis for bleeding, prompt therapy for infection, should be maintained during therapy with VESANOID (tretinoin).

There is a risk of thrombosis (both venous and arterial) which may involve any organ system, during the first month of treatment (see ADVERSE REACTIONS). Therefore, caution should be exercised when treating patients with the combination of VESANOID (tretinoin) and anti-fibrinolytic agents, such as tranexamic acid, aminocaproic acid or aprotinin (see DRUG INTERACTIONS).

The ability to drive or operate machinery might be impaired in patients treated with VESANOID (tretinoin) , particularly if they are experiencing dizziness or severe headache.

Microdosed progesterone preparations ("minipill") may be an inadequate method of contraception during treatment with VESANOID (tretinoin).

Laboratory Tests

The patient's hematologic profile, coagulation profile, liver function test results, and triglyceride and cholesterol levels should be monitored frequently.

Carcinogenesis, Mutagenesis and Impairment of Fertility

No long-term carcinogenicity studies with tretinoin have been conducted. In short-term carcinogenicity studies, tretinoin at a dose of 30 mg/kg/day (about 2 times the human dose on a mg/m² basis) was shown to increase the rate of diethylnitrosamine (DEN)-induced mouse liver adenomas and carcinomas. Tretinoin was negative when tested in the Ames and Chinese hamster V79 cell HGPRT assays for mutagenicity. A twofold increase in the sister chromatid exchange (SCE) has been demonstrated in human diploid fibroblasts, but other chromosome aberration assays, including an in vitroassay in human peripheral lymphocytes and an in vivo mouse micronucleus assay, did not show a clastogenic or aneuploidogenic effect. Adverse effects on fertility and reproductive performance were not observed in studies conducted in rats at doses up to 5 mg/kg/day (about 2/3 the human dose on a mg/m² basis). In a 6-week toxicology study in dogs, minimal to marked testicular degeneration, with increased numbers of immature spermatozoa, were observed at 10 mg/kg/day (about 4 times the equivalent human dose in mg/m²).

Nursing Mothers

It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, and because of the potential for serious adverse reactions from VESANOID (tretinoin) in nursing infants, mothers should discontinue nursing prior to taking this drug.

Pediatric Use

There are limited clinical data on the pediatric use of VESANOID (tretinoin). Of 15 pediatric patients (age range: 1 to 16 years) treated with VESANOID (tretinoin) , the incidence of complete remission was 67%. Safety and effectiveness in pediatric patients below the age of 1 year have not been established. Some pediatric patients experience severe headache and pseudotumor cerebri, requiring analgesic treatment and lumbar puncture for relief. Increased caution is recommended in the treatment of pediatric patients. Dose reduction may be considered for pediatric patients experiencing serious and/or intolerable toxicity; however, the efficacy and safety of VESANOID (tretinoin) at doses lower than 45 mg/m²/day have not been evaluated in the pediatric population.

Geriatric Use

Of the total number of subjects in clinical studies of VESANOID (tretinoin) , 21.4% were 60 and over. No overall differences in safety or effectiveness were observed between these subjects and younger subjects, and other reported clinical experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out.

SIDE EFFECTS

Virtually all patients experience some drug-related toxicity, especially headache, fever, weakness, and fatigue. These adverse effects are seldom permanent or irreversible nor do they usually require interruption of therapy. Some of the adverse events are common in patients with APL, including hemorrhage, infections, gastrointestinal hemorrhage, disseminated intravascular coagulation, pneumonia, septicemia, and cerebral hemorrhage. The following describes the adverse events, regardless of drug relationship, that were observed in patients treated with VESANOID (tretinoin).

Typical Retinoid Toxicity

The most frequently reported adverse events were similar to those described in patients taking high doses of vitamin A and included headache (86%), fever (83%), skin/mucous membrane dryness (77%), bone pain (77%), nausea/vomiting (57%), rash (54%), mucositis (26%), pruritus (20%), increased sweating (20%), visual disturbances (17%), ocular disorders (17%), alopecia (14%), skin changes (14%), changed visual acuity (6%), bone inflammation (3%), visual field defects (3%).

RA-APL Syndrome

APL patients treated with VESANOID (tretinoin) have experienced a potentially fatal syndrome characterized by fever, dyspnea, acute respiratory distress, weight gain, radiographic pulmonary infiltrates, pleural and pericardial effusions, edema, and hepatic, renal, and multi-organ failure. This syndrome has occasionally been accompanied by impaired myocardial contractility and episodic hypotension and has been observed with or without concomitant leukocytosis. Some patients have expired due to progressive hypoxemia and multi-organ failure. The syndrome generally occurs during the first month of treatment, with some cases reported following the first dose of VESANOID (tretinoin). The management of the syndrome has not been defined rigorously, but high-dose steroids given at the first signs of the syndrome appear to reduce morbidity and mortality. Treatment with dexamethasone, 10 mg intravenously administered every 12 hours for 3 days or until resolution of symptoms, should be initiated without delay at the first suspicion of symptoms (one or more of the following: fever, dyspnea, weight gain, abnormal chest auscultatory findings or radiographic abnormalities). Sixty percent or more of patients treated with VESANOID (tretinoin) may require high-dose steroids because of these symptoms. The majority of patients do not require termination of VESANOID (tretinoin) therapy during treatment of the syndrome.

Body as a Whole

General disorders related to VESANOID (tretinoin) administration and/or associated with APL included malaise (66%), shivering (63%), hemorrhage (60%), infections (58%), peripheral edema (52%), pain (37%), chest discomfort (32%), edema (29%), disseminated intravascular coagulation (26%), weight increase (23%), injection site reactions (17%), anorexia (17%), weight decrease (17%), myalgia (14%), flank pain (9%), cellulitis (8%), face edema (6%), fluid imbalance (6%), pallor (6%), lymph disorders (6%), acidosis (3%), hypothermia (3%), ascites (3%).

Respiratory System Disorders

Respiratory system disorders were commonly reported in APL patients administered VESANOID (tretinoin). The majority of these events are symptoms of the RA-APL syndrome (see boxed WARNINGS). Respiratory system adverse events included upper respiratory tract disorders (63%), dyspnea (60%), respiratory insufficiency (26%), pleural effusion (20%), pneumonia (14%), rales (14%), expiratory wheezing (14%), lower respiratory tract disorders (9%), pulmonary infiltration (6%), bronchial asthma (3%), pulmonary edema (3%), larynx edema (3%), unspecified pulmonary disease (3%).

Ear Disorders

Ear disorders were consistently reported, with earache or feeling of fullness in the ears reported by 23% of the patients. Hearing loss and other unspecified auricular disorders were observed in 6% of patients, with infrequent (<1%) reports of irreversible hearing loss.

Gastrointestinal Disorders

GI disorders included GI hemorrhage (34%), abdominal pain (31%), other gastrointestinal disorders (26%), diarrhea (23%), constipation (17%), dyspepsia (14%), abdominal distention (11%), hepatosplenomegaly (9%), hepatitis (3%), ulcer (3%), unspecified liver disorder (3%).

Cardiovascular and Heart Rate and Rhythm Disorders

Arrhythmias (23%), flushing (23%), hypotension (14%), hypertension (11%), phlebitis (11%), cardiac failure (6%) and for 3% of patients: cardiac arrest, myocardial infarction, enlarged heart, heart murmur, ischemia, stroke, myocarditis, pericarditis, pulmonary hypertension, secondary cardiomyopathy.

Central and Peripheral Nervous System Disorders and Psychiatric

Dizziness (20%), paresthesias (17%), anxiety (17%), insomnia (14%), depression (14%), confusion (11%), cerebral hemorrhage (9%), intracranial hypertension (9%), agitation (9%), hallucination (6%) and for 3% of patients: 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, tremor, leg weakness, unconsciousness, dementia, forgetfulness, somnolence, slow speech.

Urinary System Disorders

Renal insufficiency (11%), dysuria (9%), acute renal failure (3%), micturition frequency (3%), renal tubular necrosis (3%), enlarged prostate (3%).

Miscellaneous Adverse Events

Isolated cases of erythema nodosum, basophilia and hyperhistaminemia, Sweet's syndrome, organomegaly, hypercalcemia, pancreatitis and myositis have been reported.

Additional Adverse Reactions Reported With VESANOID (tretinoin)

Cardiovascular

Cases of thrombosis (both venous and arterial) involving various sites (eg, cerebrovascular accident, myocardial infarction, renal infarct) have been reported rarely (see PRECAUTIONS: General).

Hematologic

Rare cases of thrombocytosis have been reported.

Skin

Genital ulceration

Miscellaneous Adverse Events

Rare cases of vasculitis, predominantly involving the skin, have been reported.

DRUG INTERACTIONS

Limited clinical data on potential drug interactions are available.

Drugs Metabolized By the Hepatic P450 System

As VESANOID (tretinoin) is metabolized by the hepatic P450 system, there is a potential for alteration of pharmacokinetics parameters in patients administered concomitant medications that are also inducers or inhibitors of this system. Medications that generally induce hepatic P450 enzymes include rifampicin, glucocorticoids, phenobarbital and pentobarbital. Medications that generally inhibit hepatic P450 enzymes include ketoconazole, cimetidine, erythromycin, verapamil, diltiazem and cyclosporine. To date there are no data to suggest that co-use with these medications increases or decreases either efficacy or toxicity of VESANOID (tretinoin).

Agents Known to Cause Pseudotumor Cerebri/Intracranial Hypertension (Such as Tetracyclines)

VESANOID (tretinoin) may cause pseudotumor cerebri/intracranial hypertension. Concomitant administration of VESANOID (tretinoin) and agents known to cause pseudotumor cerebri/intracranial hypertension as well might increase the risk of this condition (see WARNINGS).

Vitamin A

As with other retinoids, VESANOID (tretinoin) must not be administered in combination with vitamin A because symptoms of hypervitaminosis A could be aggravated.

Anti-fibrinolytic Agents (Such as Tranexamic Acid, Aminocaproic Acid, or Aprotinin)

Cases of fatal thrombotic complications have been reported rarely in patients concomitantly treated with VESANOID (tretinoin) and anti-fibrinolytic agents. Therefore, caution should be exercised when administering VESANOID (tretinoin) concomitantly with these agents (see PRECAUTIONS: General).

Effect of Food

No data on the effect of food on the absorption of VESANOID (tretinoin) are available. The absorption of retinoids as a class has been shown to be enhanced when taken together with food.

Virtually all patients experience some drug-related toxicity, especially headache, fever, weakness, and fatigue. These adverse effects are seldom permanent or irreversible nor do they usually require interruption of therapy. Some of the adverse events are common in patients with APL, including hemorrhage, infections, gastrointestinal hemorrhage, disseminated intravascular coagulation, pneumonia, septicemia, and cerebral hemorrhage. The following describes the adverse events, regardless of drug relationship, that were observed in patients treated with VESANOID (tretinoin).

Typical Retinoid Toxicity

The most frequently reported adverse events were similar to those described in patients taking high doses of vitamin A and included headache (86%), fever (83%), skin/mucous membrane dryness (77%), bone pain (77%), nausea/vomiting (57%), rash (54%), mucositis (26%), pruritus (20%), increased sweating (20%), visual disturbances (17%), ocular disorders (17%), alopecia (14%), skin changes (14%), changed visual acuity (6%), bone inflammation (3%), visual field defects (3%).

RA-APL Syndrome

APL patients treated with VESANOID (tretinoin) have experienced a potentially fatal syndrome characterized by fever, dyspnea, acute respiratory distress, weight gain, radiographic pulmonary infiltrates, pleural and pericardial effusions, edema, and hepatic, renal, and multi-organ failure. This syndrome has occasionally been accompanied by impaired myocardial contractility and episodic hypotension and has been observed with or without concomitant leukocytosis. Some patients have expired due to progressive hypoxemia and multi-organ failure. The syndrome generally occurs during the first month of treatment, with some cases reported following the first dose of VESANOID (tretinoin). The management of the syndrome has not been defined rigorously, but high-dose steroids given at the first signs of the syndrome appear to reduce morbidity and mortality. Treatment with dexamethasone, 10 mg intravenously administered every 12 hours for 3 days or until resolution of symptoms, should be initiated without delay at the first suspicion of symptoms (one or more of the following: fever, dyspnea, weight gain, abnormal chest auscultatory findings or radiographic abnormalities). Sixty percent or more of patients treated with VESANOID (tretinoin) may require high-dose steroids because of these symptoms. The majority of patients do not require termination of VESANOID (tretinoin) therapy during treatment of the syndrome.

Body as a Whole

General disorders related to VESANOID (tretinoin) administration and/or associated with APL included malaise (66%), shivering (63%), hemorrhage (60%), infections (58%), peripheral edema (52%), pain (37%), chest discomfort (32%), edema (29%), disseminated intravascular coagulation (26%), weight increase (23%), injection site reactions (17%), anorexia (17%), weight decrease (17%), myalgia (14%), flank pain (9%), cellulitis (8%), face edema (6%), fluid imbalance (6%), pallor (6%), lymph disorders (6%), acidosis (3%), hypothermia (3%), ascites (3%).

Respiratory System Disorders

Respiratory system disorders were commonly reported in APL patients administered VESANOID (tretinoin). The majority of these events are symptoms of the RA-APL syndrome (see boxed WARNINGS). Respiratory system adverse events included upper respiratory tract disorders (63%), dyspnea (60%), respiratory insufficiency (26%), pleural effusion (20%), pneumonia (14%), rales (14%), expiratory wheezing (14%), lower respiratory tract disorders (9%), pulmonary infiltration (6%), bronchial asthma (3%), pulmonary edema (3%), larynx edema (3%), unspecified pulmonary disease (3%).

Ear Disorders

Ear disorders were consistently reported, with earache or feeling of fullness in the ears reported by 23% of the patients. Hearing loss and other unspecified auricular disorders were observed in 6% of patients, with infrequent (<1%) reports of irreversible hearing loss.

Gastrointestinal Disorders

GI disorders included GI hemorrhage (34%), abdominal pain (31%), other gastrointestinal disorders (26%), diarrhea (23%), constipation (17%), dyspepsia (14%), abdominal distention (11%), hepatosplenomegaly (9%), hepatitis (3%), ulcer (3%), unspecified liver disorder (3%).

Cardiovascular and Heart Rate and Rhythm Disorders

Arrhythmias (23%), flushing (23%), hypotension (14%), hypertension (11%), phlebitis (11%), cardiac failure (6%) and for 3% of patients: cardiac arrest, myocardial infarction, enlarged heart, heart murmur, ischemia, stroke, myocarditis, pericarditis, pulmonary hypertension, secondary cardiomyopathy.

Central and Peripheral Nervous System Disorders and Psychiatric

Dizziness (20%), paresthesias (17%), anxiety (17%), insomnia (14%), depression (14%), confusion (11%), cerebral hemorrhage (9%), intracranial hypertension (9%), agitation (9%), hallucination (6%) and for 3% of patients: 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, tremor, leg weakness, unconsciousness, dementia, forgetfulness, somnolence, slow speech.

Urinary System Disorders

Renal insufficiency (11%), dysuria (9%), acute renal failure (3%), micturition frequency (3%), renal tubular necrosis (3%), enlarged prostate (3%).

Miscellaneous Adverse Events

Isolated cases of erythema nodosum, basophilia and hyperhistaminemia, Sweet's syndrome, organomegaly, hypercalcemia, pancreatitis and myositis have been reported.

Additional Adverse Reactions Reported With VESANOID (tretinoin)

Cardiovascular

Cases of thrombosis (both venous and arterial) involving various sites (eg, cerebrovascular accident, myocardial infarction, renal infarct) have been reported rarely (see PRECAUTIONS: General).

Hematologic

Rare cases of thrombocytosis have been reported.

Skin

Genital ulceration

Miscellaneous Adverse Events

Rare cases of vasculitis, predominantly involving the skin, have been reported.

In case of overdose with VESANOID (tretinoin) , reversible signs of hypervitaminosis A (headache, nausea, vomiting, mucocutaneous symptoms) can appear. The maximal tolerated dose in patients with myelodysplastic syndrome or solid tumors was 195 mg/m²/day. The maximal tolerated dose in pediatric patients was lower at 60 mg/m²/day. Overdosage with other retinoids has been associated with transient headache, facial flushing, cheilosis, abdominal pain, dizziness and ataxia. These symptoms have quickly resolved without apparent residual effects.

There is no specific treatment in the case of an overdose; however, it is important that the patient be treated in a special hematological unit.

Tretinoin activity is primarily due to the parent drug. In human pharmacokinetics studies, orally administered drug was well absorbed into the systemic circulation, with approximately two-thirds of the administered radiolabel recovered in the urine. The terminal elimination half-life of tretinoin following initial dosing is 0.5 to 2 hours in patients with APL. There is evidence that tretinoin induces its own metabolism. Plasma tretinoin concentrations decrease on average to one-third of their day 1 values during 1 week of continuous therapy. Mean ± SD peak tretinoin concentrations decreased from 394 89 to 138 ± 139 ng/mL, while area under the curve (AUC) values decreased from 537 ± 191 ng·h/mL to 249 ± 185 ng·h/mL during 45 mg/m² daily dosing in 7 APL patients. Increasing the dose to "correct" for this change has not increased response.

Absorption

A single 45 mg/m² (~80 mg) oral dose to APL patients resulted in a mean SD peak tretinoin concentration of 347 ± 266 ng/mL. Time to reach peak concentration was between 1 and 2 hours.

Distribution

The apparent volume of distribution of tretinoin has not been determined. Tretinoin is greater than 95% bound in plasma, predominately to albumin. Plasma protein binding remains constant over the concentration range of 10 to 500 ng/mL.

Metabolism

Tretinoin metabolites have been identified in plasma and urine. Cytochrome P450 enzymes have been implicated in the oxidative metabolism of tretinoin. Metabolites include 13-cis retinoic acid, 4-oxo trans retinoic acid, 4-oxo cis retinoic acid, and 4-oxo trans retinoic acid glucuronide. In APL patients, daily administration of a 45 mg/m² dose of tretinoin resulted in an approximately tenfold increase in the urinary excretion of 4-oxo trans retinoic acid glucuronide after 2 to 6 weeks of continuous dosing, when compared to baseline values.

Excretion

Studies with radiolabeled drug have demonstrated that after the oral administration of 2.75 and 50 mg doses of tretinoin, greater than 90% of the radioactivity was recovered in the urine and feces. Based upon data from 3 subjects, approximately 63% of radioactivity was recovered in the urine within 72 hours and 31% appeared in the feces within 6 days.