Action And Clinical Pharmacology: Isotretinoin is a drug known to improve cystic acne when taken orally. It has also shown similar activity when used for treating less severe forms of acne. While its mechanism of action is not known, studies have shown that oral isotretinoin can decrease sebum secretion and sebaceous gland size. It also affects the keratinization of the stratum corneum. These processes are important to the pathogenesis of acne vulgaris. Topical isotretinoin appears to have similar properties. It is also known that a structurally related drug, tretinoin, is effective in the treatment of acne vulgaris when used topically. Since the oral use of drugs often exposes the patient to much larger quantities of drug, systemic side effects can occur as is the case with oral isotretinoin. The topical use of drugs in dermatology can often treat the disease locally without the systemic side effects.
Indications And Clinical Uses: For the topical treatment of acne vulgaris.
Contra-Indications: In persons who demonstrate hypersensitivity to any of the listed ingredients.
Manufacturers’ Warnings In Clinical States: Isotrex is intended for external use only and should be kept away from eyes, nose, mouth, and other mucous membranes because of its irritant effect.
Do not apply to eyelids or to the skin at the corners of the eyes and mouth. Avoid the angles of the nose and nasolabial fold (if treatment in these areas is necessary, apply very sparingly). 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.
Pregnancy: Topical isotretinoin should be used by women of childbearing years only after contraceptive counselling. It is recommended that topical isotretinoin should not be used by pregnant women.
There have been rare reports of birth defects among babies born to women exposed to topical tretinoin during pregnancy. However, there are no well-controlled prospective studies of the use of topical tretinoin in pregnant women. A retrospective study of mothers exposed to topical tretinoin during the first trimester of pregnancy found no increase in the incidence of birth defects. Oral isotretinoin has been associated with teratogenicity in humans. As with all retinoids, isotretinoin administered orally at high doses is teratogenic in animals. Topical reproduction studies have been performed in rabbits at maximally tolerable dermal doses up to 60 times human dose (assuming the human dose to be 800 mg of gel/day) and have revealed no evidence of harm to the fetus due to isotretinoin when applied as Isotrex gel. Topical retinoid teratology studies in rats and rabbits have been inconclusive.
Lactation: It is not known whether isotretinoin is excreted in human milk. Nevertheless, a decision should be made whether to discontinue the drug taking into account the importance of the drug to the mother.
Precautions: Concomitant topical acne therapy should be used with caution because a cumulative irritant effect may occur, especially with the use of peeling, desquamating, or abrasive agents.
Adverse Reactions: During clinical trials, 4 of 171 patients treated with isotretinoin 0.05% gel discontinued use because of irritation. Most patients experienced some erythema (109 of 171) or peeling (104 of 171). Some patients experienced severe erythema (7 of 171) or peeling (4 of 171). Transient burning, stinging, itching, or scaling were also reported.
Symptoms And Treatment Of Overdose: Symptoms and Treatment: Acute overdosage of isotretinoin gel in humans has not been reported to date.
Dosage And Administration: The gel should be applied twice daily, in the morning and before retiring, using enough medication to cover the entire affected area.
Availability And Storage: Each g of gel contains: isotretinoin 0.05% in an alcohol-base gel. Nonmedicinal ingredients: alcohol anhydrous, butylated hydroxytoluene and hydroxypropyl cellulose. Metal tubes of 30 g. Store at 15 to 30°C.
ISOTREX® Stiefel Isotretinoin Acne Therapy