Multidisciplinary Cutaneous Lymphoma Group

Targretin®

What is Targretin®?

Targretin® (bexarotene) is a retinoid medication that is used as a treatment for cutaneous T-cell lymphoma (CTCL), and is made by Ligand® Pharmaceuticals Incorporated. Bexarotene is a type of subclass of retinoids that selectively activate retinoid X receptors. It can be taken as capsules orally or may also be applied as a topical gel. The topical gel is usually prescribed to patients with specific, localized plaques or tumors and the oral Targretin® is prescribed to patients who have generalized skin lesions all throughout the body.



How does Targretin® work?

Bexarotene selectively binds to retinoid X receptor subtypes and in doing so, it activates the receptors which then function to regulate the expression of genes that control cellular differentiation and production. The exact mechanism of action of Targretin® is unknown in the treatment of CTCL.



Is there anything I should know before I start using Targretin®?

Targretin® should be not used amongst patients who are pregnant, or planning to become pregnant. Both Targretin® gel and Targretin® capsules may harm a patient's unborn baby, and if a patient believes or suspects that she is possibly pregnant, than she should immediately contact her doctor and stop using Targretin®. Patients should be using an effective way of contraceptive before beginning use of this medication. Patients who are breastfeeding should also not use Targretin® as it may be harmful to the baby. Patients who have an allergy to retinoid medications should not use Targretin®. Patients who have diabetes and use insulin should be cautious of using oral Targretin® and should consult their doctors because it may enhance the action of the insulin and lead to hypoglycemia. Targretin® oral capsules is also associated with reversible hypertriglyceridemia (elevated triglyceride content in the blood) and hypothyroidism (decreased thyroid production), and thus lipid levels and thyroid hormone levels should be checked frequently. Here at Stanford Medical, patients are prescribed with an antilipemic medication and thyroid hormone replacement starting 7 to 10 days prior to beginning the oral Targretin® treatment.



How long will it take for Targretin® to work for me?

Both Targretin® topical gel and oral capsules take time to see improvement. Patients may see improvements as early as four weeks, but most patients require a much longer time. Most patients usually are able to experience best results after about 48 to 62 weeks of treatment, given that they have stuck to the treatment schedule regularly. For best results, patients should continue to use Targretin® even after they begin to see result, as further improvements may still occur.



Are there any drugs or foods I should avoid while using Targretin®?

Vitamin A in large doses may cause some side effects and so patients should not take more than the recommended daily dosage (4000 to 5000 IU) of vitamin A. Patients who take multivitamins should check labels to see how much vitamin A they contain. Patients using Targretin® should not use the medication Gemfibrozil (Lopid®) at the same time due to elevated Targretin® levels and extremely high triglyceride levels. Patients using Targretin® gel should not use any insect repellants containing the ingredient called "DEET" (N,N-diethyl-m-toluamide). There are no known foods that have contraindications with Targretin® gel or capsules.



Are there any potential risks or side effects?

Patients who have renal insufficiency, hepatic insufficiency, diabetes mellitus, or a history of hypertriglyceridemia or pancreatitis should notify their physician and should be more cautious while using Targretin® gel or capsules. Rarely, reversible cytopenias (most leucopenia-when the number of white blood cells decreases) and liver function test abnormalities can be seen. Rare cases of acute pancreatitis have also been reported. The development of new cataracts or the worsening of previous cataracts is are, but is a potential risk associated with using oral Targretin®, and thus it is recommending that patients receive an ophthalmologic evaluation prior to initiating therapy. To prevent or foresee potential risks, patients should regularly receive blood tests to check levels of triglycerides and thyroid hormones.

Potential adverse side effects of Targretin® gel are usually skin irritation (such as itching, burning, redness, or rashes). In most cases, these side effects were mild or moderate but some patients could experience more severe forms of skin irritation. Should a patient experience such side effects, they should notify their doctors. Targretin® oral capsules may possibly experience a wider range of side effects, such as chills, fatigue/lethargy, headache, weakness/debility, rash, nausea, abdominal pain, infection, peripheral edema (excessive amounts of watery fluid in cells), and dry skin. If any side effects that are listed (or unlisted) are felt, patients should notify their doctor. Both Targretin® gel and capsules may cause sensitivity to sunlight and patients should avoid prolonged exposure to sunlight or any other ultraviolet (UV) lights.



Instructions on using Targretin®:

Targretin® Gel

  1. Apply Targretin® with a washed finger and carefully place a generous coating directly on the whole surface of each lesion with some gel visible on the surface of each lesion.
  2. Be careful to not get the gel on the surround healthy to help avoid irritation or redness.
  3. Immediately wash your hands after apply Targretin® gel with soap and water.
  4. Wait 5 to 10 minutes for the gel to dry before covering the area with clothing.
  5. Try using a mild, non-deodorant soap for bathing. When you apply the gel after you shower, wait 20 minutes before application.
  6. Targretin® is for external use only and should not be apply to sensitive tissue.
  7. Avoid showering, bathing, or swimming for at least 3 ours after any application of Targretin® gel.
  8. Avoid using other topical skin products on your treated areas (unless instructed to) and avoid scratching the area.
    Avoid covering treated areas with any bandage or material other than loose clothing.

Application Schedule

Targretin® Capsules

Targretin® oral capsules are supplied in 75 mg and should be taken with a meal (dinner is usually preferred). The recommended dose is 200 to 300 mg/m2/day. At Stanford, we recommend starting at a dose of 150 to 300 mg daily and increasing the dose by 75 to 150 mg every 1 to 2 weeks as tolerated until the maximum desired dose of 200 to 300 mg/ m2/day is attained.



Contact Information

Los Altos Pharmacy
225 2nd Street
Los Altos, CA 94002
(650) 948-1212/ (650) 949-8662

Santa Clara Drug Pharmacy
2453 Forest Ave.
Santa Clara, CA 95051
(408) 248-2790/ Fax: (408) 248-2790

Ligand Pharmaceuticals Incorporated
1-800-964-5836
www.ligand.com

 


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