VITAMIN A ACID
Dermik Laboratories Canada
Action And Clinical Pharmacology: The interest in oral vitamin A in the treatment of acne started some 30 years ago following publication of a report by Straumfjord and theoretical support for the use of the vitamin in the reduction of hyperkeratosis came from basic science investigations. Hunter and Pinkus showed a reduction in the number of keratinocytes in the human stratum corneum during oral vitamin A therapy. Fell and Mellanby noticed a suppression of keratinization by excessive vitamin A in tissue culture. This led to the opinion that vitamin A is antikeratinizing.
Topical use of vitamin A was suggested as a means of reducing systemic toxicity from vitamin A taken orally and a number of topical forms of vitamin A were tried. Topical tretinoin was found to be the most potent because of its greater peeling action.
Topical tretinoin has a very pronounced keratolytic action according to both Von Beer and Von Stuttgen. This action has led to its use in a number of dermatological conditions. It was tried successfully by Kligman et al in the treatment of acne vulgaris since follicular hyperkeratosis is considered as being an initial stage of acne.
Indications And Clinical Uses: For topical application in the treatment of acne vulgaris, primarily Grades I, II and III in which comedones, papules and pustules predominate.
Contra-Indications: Use should be discontinued if hypersensitivity to any of the ingredients is noted.
Manufacturers’ Warnings In Clinical States: Pregnancy: Topical tretinoin should be used by women of childbearing years only after contraceptive counseling. It is recommended that topical tretinoin 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. Topical retinoid teratology studies in rats and rabbits have been inconclusive. As with all retinoids, tretinoin administered orally at high doses is teratogenic.
When applying topical tretinoin, care should be taken not to apply near the eyes, mouth, angles of the nose and mucous membranes. Topical use may cause severe local redness and peeling at the site of the application. If the degree of local irritation warrants, use the medication less frequently, discontinue use temporarily, or discontinue use completely, and consult your physician.
Precautions: Concomitant topical medications and particularly other peeling agents should be used with caution. In case of a change of medications to topical tretinoin, it would be advisable to wait until peeling from previous medications has subsided.
Because of an increased susceptibility to sunlight in patients with sunburn, the use of a topical tretinoin is not advisable until the skin has fully recovered. Exposure to sunlight, including sunlamps, should be minimized during treatment with topical tretinoin.
Adverse Reactions: In certain very sensitive patients, the skin may get to be very erythematous, edematous, blistered or crusted. In such cases, application of topical tretinoin should be discontinued until the skin has fully recovered; further application should be at a level that the individual can tolerate. Temporary hyper or hypopigmentation can occur with repeated application of topical tretinoin. Increased susceptibility to sunlight has been reported. All adverse reactions seem to be reversible when treatment is discontinued.
Symptoms And Treatment Of Overdose: Symptoms and Treatment: Topical tretinoin if used excessively, may cause marked erythema, severe peeling of the skin and discomfort; on the other hand, excessive application may not bring more rapid or better results. Amount or frequency of application should be reduced if undesirable reactions occur.
Inadvertent oral ingestion of topical tretinoin may lead to the same adverse effects as those associated with excessive oral intake of vitamin A including teratogenesis in women of childbearing years. Therefore, in such cases, pregnancy testing should be carried out in women of childbearing years.
Dosage And Administration: Apply daily, preferably before retiring, where acne lesions are present, using enough of the gel or cream to lightly cover the affected area. An exacerbation of the inflammatory lesions may take place during the early weeks of application. These result from the action of the topical tretinoin on deep and previously unseen comedones and papules. Therapeutic results should be seen after 2 to 4 weeks of treatment. Results may take 6 to 8 weeks before reaching optimal degree. Once the acne lesions have responded satisfactorily, improvement can be maintained with less frequent application.
In cases of severe erythema at an early stage of treatment, the frequency of application and amount may be reduced at the beginning of treatment and then increased progressively.
Availability And Storage: Cream: Each g of cream contains: tretinoin USP 0.01%, 0.025%, 0.05% or 0.1%. Also contains 2-Bromo-2-nitropropane-1,3-diol. Tubes of 25 g (0.01, 0.025, 0.05 and 0.1%) and 50 g (0.05%).
Gel: Each g of gel contains: tretinoin USP 0.01%, 0.025% or 0.05%. Also contains methylparaben and propylparaben. Tubes of 25 and 50 g.
Store at controlled room temperature (15 to 30°C).
VITAMIN A ACID Dermik Laboratories Canada Tretinoin Acne Therapy
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