Preparation tretinoin

An example of a cutaneous preparation in which an antioxidant - butylhydroxytoluene - is added to prevent oxidation of the active substance is a tretinoin cutaneous solution (Table 12.11). During preparation tretinoin has to be protected from light and no metal utensils should be used. 

Antibacterial preparations that may be used topically in acne include erythromycin, tetracycline and clindamycin. Isotretinoin is a tretinoin isomer used in the management of acne. 

Sulfur, resorcinol, benzoyl peroxide, or salicylic acid Caut ous y use concomitant topical medications because of possible interactions with tretinoin. Significant skin irritation may result. It also is advisable to rest a patient s skin until the effects of such preparations subside before use of tretinoin is begun. 

There are many retinol containing preparations to treat vitamin deficiency states. Retinoids are also used to treat dermatological diseases like acne, psoriasis, Darier s disease, and ichthyosis. Tretinoin, all-trans-retinoic acid, is a topical preparation while isotretinoin or 13-cis-retinoic acid, and etretinate are available for oral administration. 

There are many types of preparations that contain retinol. Absorption is greatest for aqueous preparations, intermediate for emulsions, and slowest for oil solutions. Whereas oil-soluble preparations may lead to greater hepatic storage of the vitamin, water-miscible preparations usually provide higher concentrations in plasma. Vitamin A is available as capsules. Tretinoin (all-trans-retinoic acid Retin A) is available for topical use. Isotretinoin (13-ri.s-retinoic acid Accutane) is available for oral use, as is etretinate (Tegison). 

Brisaert MG, Everaerts I, Plaizier-Vercammen JA. Chemical stability of tretinoin in dermatological preparations. Pharm Acta Helv 1995 70(2) 161-166. 

The products usually used to prepare the skin are sunscreens, tretinoin, AHAs and tyrosinase inhibitors. Jess-ner s solution is sometimes used as a pre-peel preparation. It is often necessary to take measures to prevent infection, especially herpes. 

This dermatitis is in fact a positive side-effect when tretinoin is used to prepare for a TCA-SAS peel, at least to... 

Preparation with AHAs or tretinoin reduces the thickness of the stratum corneum, the skin s natural barrier. As the barrier is not as thick, it is easier for the products applied to the skin to penetrate to the basal layer of the epidermis and more deeply into the dermis. It should be noted that not aU peels require this kind of preparation. ... 

The skin does not have the same thickness aU over, and this can produce differences in the level of penetration. Correct preparation with AHAs and/or tretinoin tends to even out the thickness of the skin and allow the active products of the peel to penetrate evenly. 

Areas of hyperkeratosis (senile keratoses, and flat and seborrheic warts) are a perfect example of this difference in the level of penetration. Keratoses, which are characterized by a localized thickening of the stratum corneum, are less permeable to the acids. Pre-peel preparation with tretinoin evens out the thickness of the stratum corneum and hence the overall permeability of the epidermis. 

Preparing the skin with tretinoin before the peel accelerates post-peel healing. 

The histological features of melasma and chloasma are discussed elsewhere in this book. The standard recommendations for treatment often only mention topical applications of tretinoin, hydroquinone and other tyrosinase inhibitors corticosteroids and peels are considered as a last resort because of their potential to turn melasma into post-inflammatory hyperpigmentation (PIH). Conventional peels require conscientious pre-peel preparation to avoid this danger. Easy TCA (ETCA), in combination with appropriate post-peel care, can be used to treat melasma without the constraints of pre-peel preparation (Eigures 16.1-16.5). 

The best results are achieved when the skin has been prepared for 15 days beforehand see Chapter 2. If the skin has been prepared with tretinoin or alpha-hydroxy acids (AHAs), if the patient has used products (benzoyl peroxide) or techniques (scrub, or abrasion with a massage glove) that increase the permeability of the stratum corneum, the resorcinol paste should not be left on too long. 

Two reformulations of tretinoin include a porous bead (0.01% gel) (microspheres) and liquid polymer (0.025% cream and 0.025% gel). These are less irritating than standard vehicles for tretinoin. In the topical gel formulation containing polyolprepolymer-2, tretinoin penetration was signiflcantly reduced while epidermal deposition was enhanced, compared with a commercially available gel preparation at the same concentration. Polyolprepolymer-2 promotes retention of drug molecules on the skin surface and in the upper layers of the skin. ... 

Tretinoin became available as a topical treatment for acne in the United States in 1971. Tretinoin is also known by its chemical name, z)X-trans-retinoic acid. It increases the turnover of skin cells at the surface of the hair follicle. This leads to the extrusion of comedones. Side effects include local skin irritation and increased stm sensitivity. Newer preparations of tretinoin, designed to achieve slow absorption of the drug into epithelial cells, cause less skin irritation than forms available initially. Improvement in acne may not be noticeable until two to three weeks after treatment begins. 

Tretinoin, (vitamin A acid, retinoic acid,) is a counter-irritant effective in some types of acne it is also used in psoriasis, with doubtful efficiency. Contact allergy to locally applied retinoic acid has been reported (Lindgren et al. 1976). Patch testing with the commercial preparations containing 0.05% vitamin A acid and with vitamin A acid 0.05% in alcohol is recommended. 

Cutaneous preparations can usually be stored at room temperature. In case of chemical instability or microbiological vulnerability storage in the fridge (2-8 °C) may be necessary. For example a hydrophilic cream with diltiazem hydrochloride for rectal application (Table 12.1) and preparations that contain tretinoin are kept at low temperature to reduce the degradation rate. A zinc oxide cutaneous suspension (Table 12.21) is microbiologically vulnerable and therefore has to be stored in the fridge. 

An example for a physically stable w/o cream base is given in Table 12.32. It consists of Emulsifying Hydrophobic Base Gel (Table 12.26) and an aqueous phase preserved with sorbic acid (using a combination of potassium sorbate and citric acid). The base contains 65 % of water and is free of wool fat. It is for example an appropriate base for corticosteroids, urea, tretinoin and triclosan. The active substance lauromacrogol 400 can only be added to a base with less water. Otherwise the preparation becomes physically unstable. 

Some active substances are so sensitive to light that light must be excluded to the highest possible extent during preparation. In practice, this means that the preparation should not be done in the vicinity of a window and that artificial lights should be switched off. Examples of pharmaceutical preparations for which this may be necessary are dithranol cream, phytomenadione oral solution and tretinoin solution. 

Caution must be exercised with these kinds of substances and they need to be stored properly and not being used if the expiry date is exceeded. The influence of light should not be underestimated. The Ph. Eur. states for many substances, for example tretinoin, phytomenadione, corticosteroids and benzodiazepines that they must be protected against light. In oils and fats oxidation and peroxide formation is increased by light. Sorbic acid in solution (so also in preparations) is sensitive to light. 

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