ISOTRETINOIN (13-CIS-RETINOIC ACID)

ISOTRETINOIN (13-cis-RETINOIC ACID) (eye-soe-tret'i-noyn) Accutane, Claravis Classifications: antiacne (retinoid); Therapeutic: antiacne; antineoplastic Pregnancy Category: X

Availability

10 mg, 20 mg, 40 mg capsules

Action

Highly toxic metabolite of retinol (vitamin A). Principal actions: regulation of cell (e.g., epithelial) differentiation and proliferation and of altered lipid composition on skin surface. Decreases sebum secretion by reducing sebaceous gland size; inhibits gland cell differentiation; blocks follicular keratinization.

Therapeutic Effect

Has antiacne properties and may be used as a chemotherapeutic agent for epithelial carcinomas.

Uses

Treatment of severe recalcitrant cystic or conglobate acne in patient unresponsive to conventional treatment, including systemic antibiotics.

Unlabeled Uses

Lamellar ichthyosis, oral leukoplakia, hyperkeratosis, acne rosacea, scarring gram-negative folliculitis; adjuvant therapy of basal cell carcinoma of lung and cutaneous T-cell lymphoma (mycosis fungoides); psoriasis; chemoprevention for prostate cancer.

Contraindications

Tinnitus; hypersensitivity to parabens (preservatives in the formulation), retinoid hypersensitivity, leukopenia, neutropenia; UV exposure; pregnancy (category X), females of childbearing age, lactation.

Cautious Use

Coronary artery disease; major depression, psychosis, history of suicides, alcoholism; hepatitis, hepatic disease; visual disturbance; rheumatologic disorders, osteoporosis; history of pancreatitis, inflammatory bowel disease; diabetes mellitus; obesity; retinal disease; elevated triglycerides, hyperlipidemia.

Route & Dosage

Cystic Acne Adult: PO 0.5–1 mg/kg/d in 2 divided doses (max: recommended dose 2 mg/kg/d) Disorders of Keratinization Adult: PO Up to 4 mg/kg/d in divided doses

Administration

Oral

• Give with or shortly after meals.
• Reassess regimen after 2 wk of treatment and dose adjusted as warranted.
• Note: A single course of therapy provides adequate control in many patients. If a second course is necessary, it is delayed at least 8 wk because improvement may continue without the drug.
• Store in tight, light-resistant container. Capsules remain stable for 2 y.

Adverse Effects (≥1%)

Body as a Whole: Most are dose-related (i.e., occurring at doses >1 mg/kg/d), reversible with termination of therapy. CNS: Lethargy, headache, fatigue, visual disturbances, pseudotumor cerebri, paresthesias, dizziness, depression, psychosis, suicide (rare). Special Senses: Reduced night vision, dry eyes, papilledema, eye irritation, conjunctivitis, corneal opacities. GI: Dry mouth, anorexia, nausea, vomiting, abdominal pain, nonspecific GI symptoms, acute hepatotoxic reactions (rare), inflammation and bleeding of gums, increased AST, ALT, acute pancreatitis. Hematologic: Decreased Hct, Hgb, elevated sedimentation rate. Musculoskeletal: Arthralgia; bone, joint, and muscle pain and stiffness; chest pain, skeletal hyperostosis (especially in athletic people and with prolonged therapy), mild bruising. Skin: Cheilitis, skin fragility, dry skin, pruritus, peeling of face, palms, and soles; photosensitivity (photoallergic and phototoxic), erythema, skin infections, petechiae, rash, urticaria, exaggerated healing response (painful exuberant granulation tissue with crusting), brittle nails, thinning hair. Respiratory: Epistaxis, dry nose. Metabolic: Hyperuricemia, increased serum concentrations of triglycerides by 50–70%, serum cholesterol by 15–20%, VLDL cholesterol by 50–60%, LDL cholesterol by 15–20%.

Interactions

Drug: vitamin a supplements increase toxicity; decreases effectiveness of estrogen hormonal contraceptives in oral form as well as topical/injectable/implantable/insertable estrogen hormonal birth control.

Pharmacokinetics

Absorption: Rapid absorption after slow dissolution in GI tract; 25% of administered drug reaches systemic circulation. Peak: 3.2 h. Distribution: Not fully understood; appears in liver, ureters, adrenals, ovaries and lacrimal glands. Metabolism: In liver; enterohepatically cycled. Elimination: In urine and feces in equal amounts. Half-Life: 10–20 h.

Nursing Implications

Assessment & Drug Effects

• Lab tests: Determine baseline blood lipids at outset of treatment, then at 2 wk, 1 mo, and every month thereafter throughout course of therapy; liver function tests at 2- or 3-wk intervals for 6 mo and once a month thereafter during treatment.
• Report signs of liver dysfunction (jaundice, pruritus, dark urine) promptly.
• Monitor closely for loss of glycemic control in diabetic and diabetic-prone patients.
• Monitor for development of depression and suicidal ideation.
• Note: Persistence of hypertriglyceridemia (levels above 500–800 mg/dL) despite a reduced dose indicates necessity to stop drug to prevent onset of acute pancreatitis.

Patient & Family Education

• Maintain drug regimen even if during the first few weeks transient exacerbations of acne occur. Recurring symptoms may signify response of deep unseen lesions.
• Discontinue medication at once and notify physician if visual disturbances occur along with nausea, vomiting, and headache.
• Rule out pregnancy within 2 wk of starting treatment. Use a reliable contraceptive 1 mo before, throughout, and 1 mo after therapy is discontinued.
• Do not self-medicate with multivitamins, which usually contain vitamin A. Toxicity of isotretinoin is enhanced by vitamin A supplements.
• Avoid or minimize exposure of the treated skin to sun or sunlamps. Photosensitivity (photoallergic and phototoxic) potential is high; risk of skin cancer may be increased by this drug.
• Notify physician immediately of abdominal pain, rectal bleeding, or severe diarrhea, which are possible symptoms of drug-induced inflammatory bowel disease.
• Keep lips moist and softened (use thin layer of lubricant such as petroleum jelly); dry mouth and cheilitis (inflamed, chapped lips), frequent adverse effects of isotretinoin.
• Notify physician of joint pain, such as pain in the great toe (symptom of gout and hyperuricemia).

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Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug