Dermatological therapy

Future generations of such receptor subtype-selective retinoids or also retinobenzoic acids [3] may provide clinicians with more specific and less toxic diugs for dermatologic therapy. 

Retinoids. Table 1 Indications and mode of administration of commercially available retinoids in dermatological therapy... 

Kligman D (2001) Technologies for cutaneous exfoliation using salicylic acid. Dermatologic Therapy 14 225-227... 

Roberts WE (2004) Chemical peeling in ethnic/-dark skin. Dermatologic Therapy 17 196... 

Lever R. (1996). Infection in atopic dermatitis. Dermatology Therapy 1 32-37. 

Salicylic acid has been extensively used in dermatologic therapy as a keratolytic agent. The mechanism by which it produces its keratolytic and other therapeutic effects is poorly understood. The drug may solubilize cell surface proteins that keep the stratum corneum intact, thereby resulting in desquamation of keratotic debris. Salicylic acid is keratolytic in concentrations of 3-6%. In concentrations greater than 6%, it can be destructive to tissues. 

Salicylic acid was chemically synthesized in 1860 and has been extensively used in dermatologic therapy as a keratolytic agent. It is a white powder quite soluble in alcohol but only slightly soluble in water. 

With a few exceptions, the use of metallic mercury in medicine is considered to be outdated the few exceptions include its use in certain preservatives and in dental amalgam. The radioactive nuclides Hg and ° Hg have been used diagnostically, but the amount of mercury involved is very small. Even the mercury thermometer is rapidly being replaced by safer alternative devices. The use of mercury in dermatological therapy should be abandoned because of the risk of mercury intoxication (1). 

Fig. 13.5 How IL-1 andTNF-a cause inflammation, (a) IL-1 function. IL-1 induces the secretion of TNF-a to enhance its actions. The major effect of IL-1 is on capillary endothelial cells (see text). IL-1 causes keratinocytes and endothelial cells to proliferate and secrete other interleukins, especially IL-8, which acts like IL-1 on capillary endothelial cells (b) TNF-afunction. TNF-a usually acts as a proinflammatory growth and survival factor (see text). Its induction of vascular endothelial growth factor (VEGF) promotes greater capillary proliferation and permeability. VEGF contains a cysteine knot domain like von Willebrand factor (Fig. 11.2) [a Based on Fig. 1 in Dinarello CA (2000) Proinflammatory Cytokines. Chest 118(2) 503-508 b Slightly modified Fig. 1 from Jackson JM (2007) TNF-a inhibitors, Dermatologic Therapy, 20 251-261]...

In general, the preparation of such formulations as poultices and pastes is extemporaneous, and it is unlikely that the industrial pharmaceutical formulator will be required to develop stable, safe and efficacious products of this type. Solutions and powders lack staying power (retention time) on the skin and can only afford transient relief. In modern-day pharmaceutical practice, semi-solid formulations are preferred vehicles for dermatological therapy because they remain in situ and deliver their drug payload over extended periods. In the majority of cases, therefore, the developed formulation will be an ointment, emulsion or a gel. Typical constituents for these types of formulations are shown in Table 14.5. 

The most common emulsions used in dermatological therapy are creams. These are two-phase preparations in which one phase (the dispersed or internal phase) is finely dispersed in the other (the continuous or external phase). The dispersed phase can be either hydrophobic based (oil-in-water creams, O/W) or aqueous based (water-in-oil creams, W/O). Whether a cream is O/W or W/O is dependent on the properties of the system used to stabilize the interface between the phases. Given the fact that there are two incompatible phases in close conjunction, the physical stability of creams is always tenuous, but may be maximised by the judicious selection of an appropriate emulsion stabilizing system. In most pharmaceutical emulsions, stabilizing systems are comprised of either surfactants (ionic and/or non-ionic), polymers (non-ionic polymers, polyelectrolytes or biopolymers) or mixtures of these. The most commonly used surfactant systems are sodium alkyl sulphates (anionic), alkylammonium halides... 

Basavaraj K. H., Johnsy G., Navya M. A., Rashmi R., Siddaramaiah (2010). Biopolymers as transdermal drug delivery systems in dermatology therapy. CritRev Ther nig, 27,155-185. 

Urea, a physiological non-allergic substance [77, 84], has long been used in dermatological therapy. Urea can decrease reversibly the turnover of epidermal cells [41] and may also enhance the penetration of other substances into the skin [24, 77, 96]. Other effects include binding water in the horny layer, antipruritic, and reducing contact dermatitis from irritant stimuli [53> 77> 78, 84] ... 

Ditre CM 2000 Glycolic acid peels. Dermatologic Therapy 13 165-172... 

Grimes PE 2000 Agents for ethnic skin peeling. Dermatologic Therapy 13 159-164... 

Dermatologic Therapy 17 196—205 Rullan P, Lemmon J, Rullan JM 2004 The 2-day phenol... 

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