Absorption topical preparations

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. 

Topical/wsidic add and mupirocin are preferred (as they are not ordinarily used for systemic infections and therefore development of drug resistant strains is less likely to have any serious consequences). Framycetin and polymjodns are also used. Absorption of neomycin from all topical preparations can cause serious injury to the eighth cranial nerve. It is also a contact sensitiser. 

Zinc is present in a number of pharmaceuticals, the most important of which is life-sustaining insulin. Many topical preparations contain zinc as the oxide, sulfate, or stearate as an astringent or antipruritic. Some foot powders contain the antifungicidal zinc undecenoate, and zinc pyrithione is used in antidandruff shampoos. After dissolving them in acid, the topical products can be easily analyzed by either atomic emission or atomic absorption spectroscopy (49), since they contain a relatively high concentration of zinc. However, atomic absorption is approximately four orders of magnitude more sensitive than atomic emission for the determination of zinc (Table 2) and offers superior precision for the analysis of injectable insulin (50), where zinc concentrations can be as low as 4 ppm (39). 

The manufacturers of other topical preparations Solaraze 3% w/w gel and Voltarol 1% w/w gel patch) state that interactions are not anticipated due to the low level of systemic absorption, although one manufacturer still warns not to administer concurrently, by either the topical or systemic route, any medicinal product containing diclofenac or other NSAIDs. ... 

Because of the increased permeability of their skin, infants are at risk for excessive absorption and toxicity from the use of topical steroids. Although these agents are effective in decreasing inflammation and relieving pruritus, steroid use in infants for the treatment of diaper dermatitis should be limited to only the low-potency preparations.38... 

Transfer a portion of topical powder, equivalent to about 100 mg of miconazole nitrate to a 50 mL beaker, disperse in 40 mL of methanol, and mix for a minimum of 5 min. Allow to settle for 5-10 min, and filter into 100-mL beaker. Evaporate on a steam bath to dryness. Dry the residue at 105 °C for 10 minutes the infrared absorption spectrum of a potassium bromide dispersion of the residue so obtained exhibits maxima only at the same wavelengths as that of a similar preparation of USP Miconazole Nitrate RS. 

Venturini AP, Bertoli D, Marchi E Transcutaneous absorption of a topical rifamycin preparation Rifaximin (L/105). Drugs Exp Clin Res 1987 13 231-232. 

The subject of Figs. 4-6 involves another difficult topic the examination of carbonaceous materials. In order to obtain carbons prepared under controlled conditions, the pyrolysis of cellulose was studied. Fig. 4 shows just three of many spectra of pyrolysis sequences. The numerous changes in the spectra, e.g., the decline of aliphatic C-H stretching absorptions just... 

Ointments are semisolid preparations that are intended for external use. Ointments may contain either finely powdered drugs or their mixtures, liquids, and other drug forms incorporated into appropriate bases. They are applied to the skin for their physical effects as emollients (which make the skin more pliable), protectants, lubricants, and drying agents. Ointment bases are also used as vehicles in which to incorporate topical medications which exert specific effect. There are four types of ointment bases, namely, oleaginous, absorption, water removable, and water soluble bases. 

The solubility of C60 and C70 fullerenes in vegetable oils will permit to employ these molecules for topical use in creams, lotions and ointments, which are adsorbed by skin. Vegetable oils, especially olive oil, are considered excellent excipients for injectable preparation where the active principle is soluble in fats. Their absorption in the subcutaneous tissues is slow and limited and ensures a gradual release of the active principle (Adami, 1960). 

The two azoles most commonly used topically are clotrimazole and miconazole several others are available (see Preparations Available). Both are available over-the-counter and are often used for vulvovaginal candidiasis. Oral clotrimazole troches are available for treatment of oral thrush and are a pleasant-tasting alternative to nystatin. In cream form, both agents are useful for dermatophytic infections, including tinea corporis, tinea pedis, and tinea cruris. Absorption is negligible, and adverse effects are rare. 

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). 

Digestion is the preparation of feed for absorption, i.e. reduction of feed particles in size and solubility by mechanical and chemical means. A summary outline of digestion and absorption in poultry follows. This provides a basic understanding of how the feed is digested and the nutrients absorbed. Readers interested in a more detailed explanation of this topic should consult a recent text on poultry nutrition or physiology. 

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