Retigel

Retigel (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. Retigel (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 Retigel (tretinoin).

Retigel is indicated for topical application in the treatment of acne vulgaris. The safety and efficacy of the long-term use of this product in the treatment of other disorders have not been established.

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 Retigel (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 Retigel (tretinoin) , alternative therapy appropriate for acute myelogenous leukemia should be considered.

Retigel (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 Retigel (tretinoin) , unless otherwise contraindicated.

Retigel Gel, Cream or Liquid should be applied once a day, before retiring, to the skin where acne lesions appear, using enough to cover the entire affected area lightly. Liquid: The liquid may be applied using a fingertip, gauze pad, or cotton swab. If gauze or cotton is employed, care should be taken not to oversaturate it to the extent that the liquid would run into areas where treatment is not intended. Gel: Excessive application results in “pilling” of the gel, which minimizes the likelihood of over application by the patient. Application may cause a transitory feeling of warmth or slight stinging. In cases where it has been necessary to temporarily discontinue therapy or to reduce the frequency of application, therapy may be resumed or frequency of application increased when the patients become able to tolerate the treatment.

Alterations of vehicle, drug concentration, or dose frequency should be closely monitored by careful observation of the clinical therapeutic response and skin tolerance.

During the early weeks of therapy, an apparent exacerbation of inflammatory lesions may occur. This is due to the action of the medication on deep, previously unseen lesions and should not be considered a reason to discontinue therapy.

Therapeutic results should be noticed after two to three weeks but more than six weeks of therapy may be required before definite beneficial effects are seen.

Once the acne lesions have responded satisfactorily, it may be possible to maintain the improvement with less frequent applications, or other dosage forms.

Patients treated with Retigel (tretinoin) acne treatment may use cosmetics, but the area to be treated should be cleansed thoroughly before the medication is applied. (See PRECAUTIONS.)

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

Use of the product should be discontinued if hypersensitivity to any of the ingredients is noted.

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 Retigel (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 Retigel (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 Retigel (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 Retigel (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 Retigel (tretinoin) , a syndrome occurs which can be fatal (see boxed WARNINGS and ADVERSE REACTIONS).

Leukocytosis at Presentation and Rapidly Evolving Leukocytosis During Retigel Treatment

See boxed WARNINGS.

Pseudotumor Cerebri

Retinoids, including Retigel (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 Retigel (tretinoin) if test results reach >5 times the upper limit of normal values. However, the majority of these abnormalities resolve without interruption of Retigel (tretinoin) or after completion of treatment.

PRECAUTIONS

General

Retigel (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 Retigel (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 Retigel (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 Retigel (tretinoin) , particularly if they are experiencing dizziness or severe headache.

Microdosed progesterone preparations ("minipill") may be an inadequate method of contraception during treatment with Retigel (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 Retigel (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 Retigel (tretinoin). Of 15 pediatric patients (age range: 1 to 16 years) treated with Retigel (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 Retigel (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 Retigel (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.

WARNINGS

No information provided.

PRECAUTIONS

General

If a reaction suggesting sensitivity or chemical irritation occurs, use of the medication should be discontinued. Exposure to sunlight, including sunlamps, should be minimized during the use of Retigel, and patients with sunburn should be advised not to use the product until fully recovered because of heightened susceptibility to sunlight as a result of the use of tretinoin. Patients who may be required to have considerable sun exposure due to occupation and those with inherent sensitivity to the sun should exercise particular caution. Use of sunscreen products and protective clothing over treated areas is recommended when exposure cannot be avoided.

Weather extremes, such as wind or cold, also may be irritating to patients under treatment with tretinoin. Retigel (tretinoin) acne treatment should be kept away from the eyes, the mouth, angles of the nose, and mucous membranes. Topical use may induce severe local erythema and peeling at the site of application. If the degree of local irritation warrants, patients should be directed to use the medication less frequently, discontinue use temporarily, or discontinue use altogether. Tretinoin has been reported to cause severe irritation on eczematous skin and should be used with utmost caution in patients with this condition.

Carcinogenesis

Long-term animal studies to determine the carcinogenic potential of tretinoin have not been performed. Studies in hairless albino mice suggest that tretinoin may accelerate the tumorigenic potential of weakly carcinogenic light from a solar simulator. In other studies, when lightly pigmented hairless mice treated with tretinoin were exposed to carcinogenic doses of UVB light, the incidence and rate of development of skin tumors was reduced. Due to significantly different experimental conditions, no strict comparison of these disparate data is possible. Although the significance of these studies to man is not clear, patients should avoid or minimize exposure to sun.

Pregnancy

Teratogenic effects - Pregnancy Category C

Oral tretinoin has been shown to be teratogenic in rats when given in doses 1000 times the topical human dose. Oral tretinoin has been shown to be fetotoxic in rats when given in doses 500 times the topical human dose.

Topical tretinoin has not been shown to be teratogenic in rats and rabbits when given in doses of 100 and 320 times the topical human dose, respectively (assuming a 50 kg adult applies 250 mg of 0.1% cream topically). However, at these topical doses, delayed ossification of a number of bones occurred in both species. These changes may be considered variants of normal development and are usually corrected after weaning. There are no adequate and well-controlled studies in pregnant women. Tretinoin should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Nursing Mothers

It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when Retigel is administered to a nursing woman.

GELS ARE FLAMMABLE. Note: Keep away from heat and flame. Keep tube tightly closed.

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 Retigel (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 Retigel (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 Retigel (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 Retigel (tretinoin) may require high-dose steroids because of these symptoms. The majority of patients do not require termination of Retigel (tretinoin) therapy during treatment of the syndrome.

Body as a Whole

General disorders related to Retigel (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 Retigel (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 Retigel (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.

The skin of certain sensitive individuals may become excessively red, edematous, blistered, or crusted. If these effects occur, the medication should either be discontinued until the integrity of the skin is restored, or the medication should be adjusted to a level the patient can tolerate. True contact allergy to topical tretinoin is rarely encountered. Temporary hyper- or hypopigmentation has been reported with repeated application of Retigel. Some individuals have been reported to have heightened susceptibility to sunlight while under treatment with Retigel. To date, all adverse effects of Retigel have been reversible upon discontinuance of therapy (see DOSAGE AND ADMINISTRATION Section).

In case of overdose with Retigel (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.

If medication is applied excessively, no more rapid or better results will be obtained and marked redness, peeling, or discomfort may occur. Oral ingestion of the drug may lead to the same side effects as those associated with excessive oral intake of Vitamin A.