[e-farmacos] Absorcion transdermica de sulfadiacina topica (cont.)

["Madurga, Mariano" <mmadurga@agemed.es>]

Estimada Marcela,

La cantidad de farmaco absorbido dependera mucho del excipiente y disolvente de la preparacion topica (crema, pomada, linimento, etc) ademas de la forma de administración con masaje, con vendaje oclusivo, etc. Con la suldadiazina argentica (silver sulfadiazine) se han dado casos de nefrotoxicidad por cambios en los excipientes de la pomada (creo que con dietilenglicol se favorece la absorción y se potencia la nefrotoxicidad propia de este glicol) tal como se produjeron con un preparado de sulfadiazina argentica para grandes quemados en Espanha.

Anexo el texto del BNF, sept 2005:
Plasma-sulfadiazine concentrations may approach therapeutic levels with side-effects and interactions as for sulphonamides (see section 5.1.8) if large areas of skin are treated. Owing to the association of sulphonamides with severe blood and skin disorders treatment should be stopped immediately if blood disorders or rashes develop-but leucopenia developing 2-3 days after starting treatment of burns patients is reported usually to be self-limiting and silver sulfadiazine need not usually be discontinued provided blood counts are monitored carefully to ensure return to normality within a few days. Argyria may also occur if large areas of skin are treated (or if application is prolonged).

Anexo la informacion relativa del Micromedex:
2.3.1   Absorption
A)  Bioavailability 
1)  Topical 1% cream):
a)  Although silver is not appreciably absorbed systemically, sulfadiazine may be absorbed into the blood especially when the drug is applied to large areas and/or over prolonged periods of time (Akahane & Tsukada, 1982a; Ballin, 1974a; Anon, 1974; Dickinson, 1973a). Studies with radioactive silver sulfadiazine have shown essentially no absorption of silver with topical application (Grossman, 1970a).
2)  Serum sulfonamide levels are proportional to the extent of burned areas and to the amount of cream applied (Ballin, 1974a). During prolonged treatment of wounds involving extensive areas of the body, pediatric serum sulfonamide levels may approach adult therapeutic levels (8 to 12 milligrams/deciliter). Sulfadiazine concentrations as high as 9.1 mg/dl within 24 hours of topical application were reported in the serum of severely burned patients receiving silver sulfadiazine (Kulick et al, 1985). If renal function is sufficiently impaired, accumulation of sulfadiazine may occur particularly if the patient is dehydrated (Ballin, 1974a). In severely burned patients and in children, it is recommended that serum sulfa concentration be monitored (Prod Info Silvadene(R), 1999c).

Un abrazo,

Mariano Madurga Sanz
Agencia Espanhola de Medicamentos y Productos Sanitarios 28220-Majadahonda, Madrid
(Espanha)
Correo-e: mmadurga@agemed.es
Internet: www.agemed.es