Name: Acitretin Capsules
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Acitretin Capsules - Clinical Pharmacology
The mechanism of action of acitretin is unknown.
Oral absorption of acitretin is optimal when given with food. For this reason, acitretin was given with food in all of the following trials. After administration of a single 50 mg oral dose of acitretin to 18 healthy subjects, maximum plasma concentrations ranged from 196 to 728 ng per mL (mean: 416 ng per mL) and were achieved in 2 to 5 hours (mean: 2.7 hours). The oral absorption of acitretin is linear and proportional with increasing doses from 25 to 100 mg. Approximately 72% (range: 47% to 109%) of the administered dose was absorbed after a single 50 mg dose of acitretin was given to 12 healthy subjects.
Acitretin is more than 99.9% bound to plasma proteins, primarily albumin.
Metabolism:(See Pharmacokinetic Drug Interactions: Ethanol.)
Following oral absorption, acitretin undergoes extensive metabolism and interconversion by simple isomerization to its 13-cis form (cis-acitretin). The formation of cis-acitretin relative to parent compound is not altered by dose or fed/fast conditions of oral administration of acitretin. Both parent compound and isomer are further metabolized into chain-shortened breakdown products and conjugates, which are excreted. Following multiple-dose administration of acitretin, steady-state concentrations of acitretin and cis-acitretin in plasma are achieved within approximately 3 weeks.
The chain-shortened metabolites and conjugates of acitretin and cis-acitretin are ultimately excreted in the feces (34% to 54%) and urine (16% to 53%). The terminal elimination half-life of acitretin following multiple-dose administration is 49 hours (range: 33 to 96 hours), and that of cis-acitretin under the same conditions is 63 hours (range: 28 to 157 hours). The accumulation ratio of the parent compound is 1.2; that of cis-acitretin is 6.6.
In an 8-week trial of acitretin pharmacokinetics in subjects with psoriasis, mean steady-state trough concentrations of acitretin increased in a dose-proportional manner with dosages ranging from 10 to 50 mg daily. Acitretin plasma concentrations were nonmeasurable (<4 ng per mL) in all subjects 3 weeks after cessation of therapy.
In a multiple-dose trial in healthy young (n=6) and elderly (n=8) subjects, a 2-fold increase in acitretin plasma concentrations were seen in elderly subjects, although the elimination half-life did not change.
Plasma concentrations of acitretin were significantly (59.3%) lower in subjects with end-stage renal failure (n=6) when compared with age-matched controls, following single 50 mg oral doses. Acitretin was not removed by hemodialysis in these subjects.
Pharmacokinetic Drug Interactions (see also boxed CONTRAINDICATIONS AND WARNINGS and PRECAUTIONS: Drug Interactions):
In studies of in vivo pharmacokinetic drug interactions, no interaction was seen between acitretin and cimetidine, digoxin, phenprocoumon, or glyburide.
Clinical evidence has shown that etretinate (a retinoid with a much longer half-life, see below) can be formed with concurrent ingestion of acitretin and ethanol. In a 2-way crossover trial, all 10 subjects formed etretinate with concurrent ingestion of a single 100 mg oral dose of acitretin during a 3-hour period of ethanol ingestion (total ethanol, approximately 1.4 g per kg body weight). A mean peak etretinate concentration of 59 ng per mL (range: 22 to 105 ng per mL) was observed, and extrapolation of AUC values indicated that the formation of etretinate in this trial was comparable to a single 5 mg oral dose of etretinate. There was no detectable formation of etretinate when a single 100 mg oral dose of acitretin was administered without concurrent ethanol ingestion, although the formation of etretinate without concurrent ethanol ingestion cannot be excluded (see boxed CONTRAINDICATIONS AND WARNINGS). Of 93 evaluable psoriatic subjects on acitretin therapy in several foreign trials (10 to 80 mg per day), 16% had measurable etretinate levels (>5 ng per mL).
Etretinate has a much longer elimination half-life compared with that of acitretin. In one trial the apparent mean terminal half-life after 6 months of therapy was approximately 120 days (range: 84 to 168 days). In another trial of 47 subjects treated chronically with etretinate, 5 had detectable serum drug levels (in the range of 0.5 to 12 ng per mL) 2.1 to 2.9 years after therapy was discontinued. The long half-life appears to be due to storage of etretinate in adipose tissue.
It has not been established if there is a pharmacokinetic interaction between acitretin and combined oral contraceptives. However, it has been established that acitretin interferes with the contraceptive effect of microdosed progestin preparations.1 Microdosed “minipill” progestin preparations are not recommended for use with acitretin. It is not known whether other progestin-only contraceptives, such as implants and injectables, are adequate methods of contraception during acitretin therapy.
Indications and Usage for Acitretin Capsules
Acitretin Capsules, USP are indicated for the treatment of severe psoriasis in adults. Because of significant adverse effects associated with its use, Acitretin Capsules, USP should be prescribed only by those knowledgeable in the systemic use of retinoids. In females of reproductive potential, Acitretin Capsules, USP should be reserved for non-pregnant patients who are unresponsive to other therapies or whose clinical condition contraindicates the use of other treatments (see boxed CONTRAINDICATIONS AND WARNINGS Acitretin Capsules, USP can cause severe birth defects).
Most patients experience relapse of psoriasis after discontinuing therapy. Subsequent courses, when clinically indicated, have produced efficacy results similar to the initial course of therapy.
Pregnancy Category X:
(See boxed CONTRAINDICATIONS AND WARNINGS.)
Acitretin is contraindicated in patients with severely impaired liver or kidney function and in patients with chronic abnormally elevated blood lipid values (see boxed WARNINGS: Hepatotoxicity, WARNINGS: Lipids and Possible Cardiovascular Effects, and PRECAUTIONS).
An increased risk of hepatitis has been reported to result from combined use of methotrexate and etretinate. Consequently, the combination of methotrexate with acitretin is also contraindicated (see PRECAUTIONS: Drug Interactions).
Since both acitretin and tetracyclines can cause increased intracranial pressure, their combined use is contraindicated (see WARNINGS : Pseudotumor Cerebri).
Acitretin is contraindicated in cases of hypersensitivity (e.g., angioedema, urticaria) to the preparation (acitretin or excipients) or to other retinoids.
A description of the Education and Pregnancy Prevention for Acitretin (EPPATM) Program materials is provided below. The main goals of the materials are to explain the program requirements, to reinforce the educational messages, and to assess program effectiveness.
The EPPATM Program includes:
- The EPPATM Program Patient Booklet: information on the program requirements, risks of acitretin, and the types of contraceptive methods
- The Contraception Counseling Referral Form for female patients who want to receive free contraception counseling reimbursed by the manufacturer
- The Patient Agreement/Informed Consent for Female Patients form
- Medication Guide
The Education and Pregnancy Prevention for Acitretin (EPPATM) Program also includes a voluntary patient survey for women of childbearing potential to assess the effectiveness of the EPPATM Program. Education and Pregnancy Prevention for Acitretin (EPPATM) Program materials are available at www.acitretinEPPA.com or may be requested by calling 1-877-994-6729.
Information for Patients:
(See Medication Guide for all patients and Patient Agreement/Informed Consent for Female Patients at end of professional labeling.)
Patients should be instructed to read the Medication Guide supplied as required by law when Acitretin Capsules are dispensed.
Females of Reproductive Potential:
Acitretin can cause severe birth defects. Female patients must not be pregnant when therapy with acitretin is initiated, they must not become pregnant while taking acitretin and for at least 3 years after stopping acitretin, so that the drug can be eliminated to below a blood concentration that would be associated with an increased incidence of birth defects. Because this threshold has not been established for acitretin in humans and because elimination rates vary among patients, the duration of post therapy contraception to achieve adequate elimination cannot be calculated precisely (see boxed CONTRAINDICATIONS AND WARNINGS).
Females of reproductive potential should also be advised that they must not ingest beverages or products containing ethanol while taking acitretin and for 2 months after acitretin has been discontinued. This allows for elimination of the acitretin which can be converted to etretinate in the presence of alcohol.
Female patients should be advised that any method of birth control can fail, including tubal ligation, and that microdosed progestin “minipill” preparations are not recommended for use with acitretin (see CLINICAL PHARMACOLOGY: Pharmacokinetic Drug Interactions). Data from one patient who received a very low-dosed progestin contraceptive (levonorgestrel 0.03 mg) had a significant increase of the progesterone level after 3 menstrual cycles during acitretin treatment.2
Female patients should sign a consent form prior to beginning therapy with acitretin (see boxed CONTRAINDICATIONS AND WARNINGS).
Studies on lactating rats have shown that etretinate is excreted in the milk. There is one prospective case report where acitretin is reported to be excreted in human milk. Therefore, nursing mothers should not receive acitretin prior to or during nursing because of the potential for serious adverse reactions in nursing infants.
Depression and/or other psychiatric symptoms such as aggressive feelings or thoughts of self-harm have been reported. These events, including self-injurious behavior, have been reported in patients taking other systemically administered retinoids, as well as in patients taking acitretin. Since other factors may have contributed to these events, it is not known if they are related to acitretin. Patients should be counseled to stop taking acitretin and notify their prescriber immediately if they experience psychiatric symptoms.
Patients should be advised that a transient worsening of psoriasis is sometimes seen during the initial treatment period. Patients should be advised that they may have to wait 2 to 3 months before they get the full benefit of acitretin, although some patients may achieve significant improvements within the first 8 weeks of treatment as demonstrated in clinical trials.
Decreased night vision has been reported during therapy with acitretin. Patients should be advised of this potential problem and warned to be cautious when driving or operating any vehicle at night. Visual problems should be carefully monitored (see WARNINGS and ADVERSE REACTIONS). Patients should be advised that they may experience decreased tolerance to contact lenses during the treatment period and sometimes after treatment has stopped.
Patients should not donate blood during and for at least 3 years following therapy because acitretin can cause birth defects and women of childbearing potential must not receive blood from patients being treated with acitretin.
Because of the relationship of acitretin to vitamin A, patients should be advised against taking vitamin A supplements in excess of minimum recommended daily allowances to avoid possible additive toxic effects.
Patients should avoid the use of sun lamps and excessive exposure to sunlight (non-medical UV exposure) because the effects of UV light are enhanced by retinoids.
Patients should be advised that they must not give their Acitretin Capsules to any other person.
Acitretin has not been studied in and is not indicated for treatment of acne.
Significantly lower doses of phototherapy are required when acitretin is used because effects on the stratum corneum induced by acitretin can increase the risk of erythema (burning) (see DOSAGE AND ADMINISTRATION).
Clinical evidence has shown that etretinate can be formed with concurrent ingestion of acitretin and ethanol (see boxed CONTRAINDICATIONS AND WARNINGS and CLINICAL PHARMACOLOGY: Pharmacokinetics).
In a trial of 7 healthy male volunteers, acitretin treatment potentiated the blood glucose-lowering effect of glyburide (a sulfonylurea similar to chlorpropamide) in 3 of the 7 subjects. Repeating the trial with 6 healthy male volunteers in the absence of glyburide did not detect an effect of acitretin on glucose tolerance. Careful supervision of diabetic patients under treatment with acitretin is recommended (see CLINICAL PHARMACOLOGY: Pharmacokinetics and DOSAGE AND ADMINISTRATION).
It has not been established if there is a pharmacokinetic interaction between acitretin and combined oral contraceptives. However, it has been established that acitretin interferes with the contraceptive effect of microdosed progestin “minipill” preparations. Microdosed “minipill” progestin preparations are not recommended for use with acitretin (see CLINICAL PHARMACOLOGY: Pharmacokinetic Drug Interactions). It is not known whether other progestin-only contraceptives, such as implants and injectables, are adequate methods of contraception during acitretin therapy.
An increased risk of hepatitis has been reported to result from combined use of methotrexate and etretinate. Consequently, the combination of methotrexate with acitretin is also contraindicated (see CONTRAINDICATIONS).
If acitretin is given concurrently with phenytoin, the protein binding of phenytoin may be reduced.
Since both acitretin and tetracyclines can cause increased intracranial pressure, their combined use is contraindicated (see CONTRAINDICATIONS and WARNINGS: Pseudotumor Cerebri).
Vitamin A and Oral Retinoids:
Concomitant administration of vitamin A and/or other oral retinoids with acitretin must be avoided because of the risk of hypervitaminosis A.
There appears to be no pharmacokinetic interaction between acitretin and cimetidine, digoxin, or glyburide. Investigations into the effect of acitretin on the protein binding of anticoagulants of the coumarin type (warfarin) revealed no interaction.
If significant abnormal laboratory results are obtained, either dosage reduction with careful monitoring or treatment discontinuation is recommended, depending on clinical judgment.
Some patients receiving retinoids have experienced problems with blood sugar control. In addition, new cases of diabetes have been diagnosed during retinoid therapy, including diabetic ketoacidosis. In diabetics, blood-sugar levels should be monitored very carefully.
In clinical trials, the incidence of hypertriglyceridemia was 66%, hypercholesterolemia was 33%, and that of decreased HDL was 40%. Pretreatment and follow-up measurements should be obtained under fasting conditions. It is recommended that these tests be performed weekly or every other week until the lipid response to acitretin has stabilized (see WARNINGS).
Liver Function Tests:
Elevations of AST (SGOT), ALT (SGPT), or LDH were experienced by approximately 1 in 3 patients treated with acitretin. It is recommended that these tests be performed prior to initiation of therapy with acitretin, at 1- to 2-week intervals until stable, and thereafter at intervals as clinically indicated (see CONTRAINDICATIONS and boxed WARNINGS).
Carcinogenesis, Mutagenesis, Impairment of Fertility:
A carcinogenesis study of acitretin in Wistar rats, at doses up to 2 mg per kg per day administered 7 days per week for 104 weeks, has been completed. There were no neoplastic lesions observed that were considered to have been related to treatment with acitretin. An 80-week carcinogenesis study in mice has been completed with etretinate, the ethyl ester of acitretin. Blood level data obtained during this study demonstrated that etretinate was metabolized to acitretin and that blood levels of acitretin exceeded those of etretinate at all times studied. In the etretinate study, an increased incidence of blood vessel tumors (hemangiomas and hemangiosarcomas at several different sites) was noted in male, but not female, mice at doses approximately one-half the maximum recommended human therapeutic dose based on a mg-per-m2 comparison.
Acitretin was evaluated for mutagenic potential in the Ames test, in the Chinese hamster (V79/HGPRT) assay, in unscheduled DNA synthesis assays using rat hepatocytes and human fibroblasts, and in an in vivo mouse micronucleus assay. No evidence of mutagenicity of acitretin was demonstrated in any of these assays.
Impairment of Fertility:
In a fertility study in rats, the fertility of treated animals was not impaired at the highest dosage of acitretin tested, 3 mg per kg per day (approximately one-half the maximum recommended therapeutic dose based on a mg-per-m2 comparison). Chronic toxicity studies in dogs revealed testicular changes (reversible mild to moderate spermatogenic arrest and appearance of multinucleated giant cells) in the highest dosage group (50 then 30 mg per kg per day).
No decreases in sperm count or concentration and no changes in sperm motility or morphology were noted in 31 men (17 psoriatic subjects, 8 subjects with disorders of keratinization, and 6 healthy volunteers) given 30 to 50 mg per day of acitretin for at least 12 weeks. In these trials, no deleterious effects were seen on either testosterone production, LH, or FSH in any of the 31 men.4-6 No deleterious effects were seen on the hypothalamic-pituitary axis in any of the 18 men where it was measured.4,5
Pregnancy Category X (see boxed CONTRAINDICATIONS AND WARNINGS).
In a study in which acitretin was administered to male rats only at a dosage of 5 mg per kg per day for 10 weeks (approximate duration of one spermatogenic cycle) prior to and during mating with untreated female rats, no teratogenic effects were observedin the progeny (see boxed CONTRAINDICATIONS AND WARNINGS for information about male use of acitretin).
In rats dosed at 3 mg per kg per day (approximately one-half the maximum recommended therapeutic dose based on a mg-per-m2 comparison), slightly decreased pup survival and delayed incisor eruption were noted. At the next lowest dose tested, 1 mg per kg per day, no treatment-related adverse effects were observed.
Safety and effectiveness in pediatric patients have not been established. No clinical trials have been conducted in pediatric subjects. Ossification of interosseous ligaments and tendons of the extremities, skeletal hyperostoses, decreases in bone mineral density, and premature epiphyseal closure have been reported in children taking other systemic retinoids, including etretinate, a metabolite of acitretin. A causal relationship between these effects and acitretin has not been established. While it is not known that these occurrences are more severe or more frequent in children, there is special concern in pediatric patients because of the implications for growth potential (see WARNINGS: Hyperostosis).
Clinical trials of acitretin did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently than younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger subjects. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy. A 2-fold increase in acitretin plasma concentrations was seen in healthy elderly subjects compared with young subjects, although the elimination half-life did not change (see CLINICAL PHARMACOLOGY: Special Populations).
In the event of acute overdosage, acitretin must be withdrawn at once. Symptoms of overdose are identical to acute hypervitaminosis A (e.g., headache and vertigo). The acute oral toxicity (LD50) of acitretin in both mice and rats was greater than 4,000 mg per kg.
In one reported case of overdose, a 32-year-old male with Darier’s disease took 21 x 25 mg capsules (525 mg single dose). He vomited several hours later but experienced no other ill effects.
All female patients of childbearing potential who have taken an overdose of acitretin must:
1) Have a pregnancy test at the time of overdose; 2) Be counseled as per the boxed CONTRAINDICATIONS AND WARNINGS and PRECAUTIONS sections regarding birth defects and contraceptive use for at least 3 years’ duration after the overdose.
1. Berbis Ph, et al.: Arch Dermatol Res (1988) 280:388-389. 2. Maier H, Honigsmann H: Concentration of etretinate in plasma and subcutaneous fat after long-term acitretin. Lancet 348:1107, 1996. 3. Geiger JM, Walker M: Is there a reproductive safety risk in male patients treated with acitretin (Neotigason®/ Soriatane®)? Dermatology 205:105-107, 2002. 4. Sigg C, et al.: Andrological investigations in patients treated with etretin. Dermatologica 175:48-49, 1987. 5. Parsch EM, et al.: Andrological investigation in men treated with acitretin (Ro 10-1670). Andrologia 22:479-482, 1990. 6. Kadar L, et al.: Spermatological investigations in psoriatic patients treated with acitretin. In: Pharmacology of Retinoids in the Skin; Reichert U. et al., ed, KARGER, Basel, vol. 3, pp 253-254, 1988.
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