Лако-красочные материалы — производство

Nasal delivery systems are usually in the form of aqueous sprays in which the drug is distributed into the nasal cavity. This area provides an excellent route for drug absorp­tion because of its large surface area and vascularity [58] as well as a thin layer of mucus secreted from local mucosal glands [59]. Absorption into the bloodstream via the nasal route also eliminates hepatic first-pass metabolism. This combination makes the nasal cavity an excellent route for localized treatment (e. g., nasal inflammation and allergic responses) as well as for systemic drug delivery. A suitable bioadhesive could then be hydrated by the nasal mucus and form a viscous gel covering the nasal cavity. The ciliary removal of mucus must be taken into consideration when using bioadhesives in the nasal cavity.

Many researchers have taken advantage of this potential route using bioadhesives as a delivery system. Hydrophilic compounds that are normally poorly absorbed in the nasal cavity [60] can still be utilized using penetration enhancers in conjunction with a retained delivery system [61]. Using degradable starch microspheres and a penetration enhancer, the nasal absorption of gentamicin [62] was shown to be improved. These microspheres form a gel when in contact with the moist nasal mucosa. Using these degradable starch microspheres, nasal administration of insulin has been shown to be improved when admi­nistered with penetration enhancers [63]. Insulin has also been administered in freeze-dried form with Carbopol 934 (a cross-linked polyacrylic acid polymer) to achieve a sustained release effect, which increased with increasing Carbopol concentration [64]. Using poly­acrylic acid, other research has shown increased availability of both insulin and calcitonin by nasal administration in rats [65]. Using the nasal route of administration for insulin, as opposed to the daily subcutaneous injections commonly used, has obvious benefits with respect to patient compliance, although systemic levels of drug thus far are lower with the same dosage concentration, even with the addition of enhancers.