Overview
11 DESCRIPTION TARGRETIN ® (bexarotene) Capsules contain bexarotene, a member of a subclass of retinoids that selectively activate retinoid X receptors (RXRs). These retinoid receptors have biologic activity distinct from that of retinoic acid receptors (RARs). The chemical name of bexarotene is 4-[1-(5,6,7,8-tetrahydro-3,5,5,8,8-pentamethyl-2-naphthalenyl)ethenyl]benzoic acid, and the structural...
Mechanism of Action
12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action Bexarotene selectively binds and activates retinoid X receptor subtypes (RXRα, RXRß, RXRγ). RXRs can form heterodimers with various receptor partners such as retinoic acid receptors (RARs), vitamin D receptor, thyroid receptor, and peroxisome proliferator activator receptors (PPARs). Once activated, these receptors function as transcription factors that regulate the expression of genes that control cellular differentiation and proliferation. Bexarotene inhibits the growth in vitro of some tumor cell lines of hematopoietic and squamous cell origin. It also induces tumor regression in vivo in some animal models. The exact mechanism of action of bexarotene in the treatment of cutaneous T-cell lymphoma (CTCL) is unknown. 12.
Indications
- 1 INDICATIONS AND USAGE TARGRETIN ® (bexarotene) Capsules are indicated for the treatment of cutaneous manifestations of cutaneous T-cell lymphoma in patients who are refractory to at least one prior systemic therapy. TARGRETIN (bexarotene) is a retinoid indicated for the treatment of cutaneous manifestations of cutaneous T-cell lymphoma in patients who are refractory to at least one prior systemic therapy. ( 1 )
Common Doses
- 300 mg
- 75 mg
- 200 mg
- 100 mg
Dosage
2 DOSAGE AND ADMINISTRATION The recommended initial dose of TARGRETIN is 300 mg/m 2 /day (see Table 1). TARGRETIN should be taken as a single oral daily dose with a meal. For precautions to prevent pregnancy and birth defects in women of child-bearing potential [ see Use in Specific Populations (8.1) ]. Table 1: TARGRETIN Initial Dose Calculation According to Body Surface Area Initial Dose Level (300 mg/m 2 /day) Number of 75 mg TARGRETIN Capsules Body Surface Area (m 2 ) Total Daily Dose (mg/day) 0.88 – 1.12 300 4 1.13 – 1.37 375 5 1.38 – 1.62 450 6 1.63 – 1.87 525 7 1.88 – 2.12 600 8 2.
Black Box Warning
WARNING: BIRTH DEFECTS TARGRETIN is a member of the retinoid class of drugs that is associated with birth defects in humans. Bexarotene also caused birth defects when administered orally to pregnant rats. TARGRETIN must not be administered to a pregnant woman. ( 8.1 ) WARNING: BIRTH DEFECTS See full prescribing information for complete boxed warning. TARGRETIN is a member of the retinoid class of drugs that is associated with birth defects in humans. Bexarotene also caused birth defects when administered orally to pregnant rats. TARGRETIN must not be administered to a pregnant woman. ( 8.1 )
Contraindications
- 4 CONTRAINDICATIONS • Pregnancy (Boxed Warning, 4.1 ) • Known hypersensitivity to bexarotene ( 4.2 ) 4.1 Pregnancy TARGRETIN can cause fetal harm when administered to a pregnant female. TARGRETIN is a member of the retinoid class of drugs that is associated with birth defects in humans and is contraindicated in females who are pregnant. Bexarotene was also teratogenic and caused developmental mortality when administered orally to pregnant rats.
Side Effects
- 6 ADVERSE REACTIONS The following serious adverse reactions are discussed in greater detail in other sections of the prescribing information: • Hyperlipidemia [ see Warnings and Precautions (5.1) ] • Pancreatitis [ see Warnings and Precautions (5.2) ] • Hepatotoxicity, Cholestasis, and Hepatic Failure [ see Warnings and Precautions (5.3) ] • Hypothyroidism [ see Warnings and Precautions (5.4) ] • Neutropenia [ see Warnings and Precautions (5.5) ] • Cataracts [ see Warnings and Precautions (5.6) ] • Vitamin A Supplementation Hazard [ see Warnings and Precautions (5.
Interactions
- 7 DRUG INTERACTIONS Effect of Other Drugs on TARGRETIN Gemfibrozil: Concomitant administration of TARGRETIN and gemfibrozil resulted in increases in plasma concentrations of bexarotene. Concomitant administration of gemfibrozil with TARGRETIN is not recommended. Effect of TARGRETIN on Other Drugs TARGRETIN may be an inducer for the CYP3A4 enzymes, and may reduce plasma concentrations of other substrates metabolized by CYP3A4. Drug products which may be affected include oral or other systemic hormonal contraceptives.