Topical occlusion

TOPICAL CORTICOSTEROIDS. Before drug application, die nurse washes the area with soap and warm water unless the primary health care provider directs otherwise Topical corticosteroids are usually ordered to be applied sparingly. The primary health care provider also may order the area of application to be covered or left exposed to the air. Some corticosteroids are applied as an occlusive dressing. The nurse applies the drug while the skin is still moist after washing with soap and water, covers the area with a plastic wrap, seals it with tape or bandage, and leaves it in place for the prescribed period of time ... 

Application of topical corticosteroids under occlusion, or UV therapy (PUVA, UVAl) has been reported to lead to dermatologic improvement in patients with CM [9]. Both are effective in reducing pruritus and urtication, but relapse typically occurs... 

Application of topical salicylates can lead to systemic effects, especially if the product is applied liberally. Repeated application and occlusion with a wrap or bandage also can increase systemic concentrations.41 Salicylate-containing counterirritants should be used with caution in patients in whom systemic salicylates are contraindicated, such as patients with severe asthma or aspirin allergy.42 Topical salicylates have been reported to increase prothrombin time in patients on warfarin and should be used with caution in patients on oral anticoagulants.43... 

Patients prescribed topical P-blockers should be counseled on the nasolacrimal occlusion technique to decrease systemic absorption. 

Topical agents may be incorporated into various vehicles including ointments, creams, gels, lotions, foams, pastes, and shampoos. Ointments provide occlusion which may increase... 

Protectants are generally applied to the affected area after every diaper change and can be discontinued when the rash resolves. Other available protectants that can be used alone or in combination for the safe and effective treatment of diaper rash include white petrolatum, vitamins A and D, lanolin, and topical cornstarch. Many agents contain a combination of occlusive and protective agents such as Triple Paste and Calmoseptine . 

Lethal amounts of topically applied 1,2-dibromoethane were rapidly absorbed through the intact skin of rabbits. When evaporation was prevented for 24 hours by occlusive dressing, mortality occurred within 4 days (Rowe et al. 1952). 

When rabbits were exposed topically to 1,2-dibromoethane, all animals with occlusive dressings, irrespective of concentration, had moderate to severe cutaneous erythema, edema, and necrosis with sloughing (Rowe et al. 1952). When evaporation was not inhibited, slight erythema but no additional damage occurred. Lethality associated with this exposure was discussed in Section 2.2.3.1. 

Jenning, V., et al., Vitamin A loaded solid lipid nanoparticles for topical use occlusive properties and drug targeting to the upper skin. Eur. J. Pharm. Biopharm., 49, 211-18, 2000. 

Topical preparations usually contain relatively insoluble steroids, such as clobetasol propionate, triamcinolone acetonide, or triamcinolone diacetate. Side effects of this mode of drug application are usually milder and more transient than those seen after systemically administered steroids. However, potent topical corticosteroids, such as clobetasol propionate (Temovate), can suppress adrenal function when used in large amounts for a long time, especially when the skin surface is denuded or when occlusive dressings are employed. Since the high potency topical preparations carry a higher risk of local side effects, their use should be held in reserve. 

Rub topical terbinafine well into the affected and surrounding areas and do not cover the treated area with an occlusive dressing... 

Reduction in intracraniaVintraocular pressure 1-15 g/kg Maximum 120g daily. Shin/nail debridement Topical Apply urea cream, 40% to affected areas. If desired, cover with occlusive dressing. Keep dry and occlusive for 3-7 days. 

Dermopathy or pretibial myxedema will often respond to topical corticosteroids applied to the involved area and covered with an occlusive dressing. 

Pharmacokinetic studies indicate that 1-2% of the dose is absorbed when applied as a solution on the back under an occlusive dressing. Ciclopirox olamine is available as a 1% cream and lotion (Loprox) for the topical treatment of dermatomycosis, candidiasis, and tinea versicolor. The incidence of adverse reactions has been low. Pruritus and worsening of clinical disease have been reported. The potential for delayed allergic contact hypersensitivity appears small. 

Table 61-1 groups topical corticosteroid formulations according to approximate relative efficacy. Table 61-2 lists major dermatologic diseases in order of their responsiveness to these drugs. In the first group of diseases, low- to medium-efficacy corticosteroid preparations often produce clinical remission. In the second group, it is often necessary to use high-efficacy preparations, occlusion therapy, or both. Once a remission has been achieved, every effort should be made to maintain the improvement with a low-efficacy corticosteroid. 

Propylene glycol is used extensively in topical preparations because it is an excellent vehicle for organic compounds. It has been used alone as a keratolytic agent in 40-70% concentrations, with plastic occlusion, or in gel with 6% salicylic acid. 

A complication of the use of alcoholic iodine solution has been described in three women undergoing cesarean section, who developed painful, superficial, inflammatory reactions on their buttocks after skin preparation for surgery with 10% iodine in alcohol (59). These lesions were believed to have been caused by pooling of the solution underneath the patients, topical skin damage being exacerbated by heat and occlusive drapes. 

In general, increased tissue wetness promotes transdermal delivery of both hydrophilic and lipophilic permeants. However, Bucks and Maibach [3] cautioned against too wide a generalization, stating that occlusion does not necessarily increase percutaneous absorption and may not always enhance transdermal delivery of hydrophilic compounds. Further, they warned that occlusion could irritate skin with clear implications for the design and clinical application of transdermal and topical preparations. 

Barry, B.W., D. Southwell, and R. Woodford. 1984. Optimisation of bioavailability of topical steroids Penetration enhancers under occlusion. J Invest Dermatol 82 49. 

Formulation additives used in topical drug or pesticide formulations can alter the stratum comeum barrier. Surfactants are least likely to be absorbed, but they can alter the lipid pathway by fluidization and delipidization of lipids, and proteins within the keratinocytes can become denatured. This is mostly likely associated with formulations containing anionic surfactants than non-ionic surfactants. Similar effects can be observed with solvents. Solvents can partition into the intercellular lipids, thereby changing membrane lipophilicity and barrier properties in the following order ether/acetone > DMSO > ethanol > water. Higher alcohols and oils do not damage the skin, but they can act as a depot for lipophilic drugs on the skin surface. The presence of water in several of these formulations can hydrate the skin. Skin occlusion with fabric or transdermal patches, creams, and ointments can increase epidermal hydration, which can increase permeability. 

One of the most controversial topics in the recent literature, with regard to partition coefficients in carbonates, has been the effect of precipitation rates on values of the partition coefficients. The fact that partition coefficients can be substantially influenced by crystal growth rates has been well established for years in the chemical literature, and interesting models have been produced to explain experimental observations (e.g., for a simple summary see Ohara and Reid, 1973). The two basic modes of control postulated involve mass transport properties and surface reaction kinetics. Without getting into detailed theory, it is perhaps sufficient to point out that kinetic influences can cause both increases and decreases in partition coefficients. At high rates of precipitation, there is even a chance for the physical process of occlusion of adsorbates to occur. In summary, there is no reason to expect that partition coefficients in calcite should not be precipitation rate dependent. Two major questions are (1) how sensitive to reaction rate are the partition coefficients of interest and (2) will this variation of partition coefficients with rate be of significance to important natural processes Unless the first question is acceptably answered, it will obviously be difficult to deal with the second question. 

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