Лако-красочные материалы — производство

Drug administration to the oral cavity has many advantages from both a patient and a therapeutic point of view. Both local and systemic availability can be achieved using bioadhesives in the oral cavity. Anesthetic, anti-inflammatory, and antimicrobial agents can be administered locally for increased residence time using bioadhesives. Besides the use of adhesives for retention of dentures, the dental industry has taken advantage of using bioadhesives for other localized applications. The anesthetic lidocaine, used locally for toothaches, has been shown to have an increased duration of activity when administered in a mucoadhesive tablet containing a combination of freeze-dried hydroxypropyl cellulose and Carbopol 934 [72]. This has advantages over the usual forms of topical administra­tion, which show little precision in site specificity and can quickly be washed away by saliva. The analgesic lignocaine has also been studied when applied by a bioadhesive patch [73]. Various polymer systems have been employed to deliver fluorides to the oral cavity [74,75]. Others have reported therapeutic treatment of buccal lesions, such as aphthae and lichen planus using bioadhesives [76-78]. These dosage forms have the advantage over standard oral ointments of being applied directly to the lesion and achieving high drug levels because of increased duration at the site of inflammation.

Systemic delivery of drugs through the mouth has gained popularity in recent years. Drugs that are susceptible to degradation by the harshness of the gastrointestinal route can be administered via the mouth. This avoids first-pass metabolism of susceptible com­pounds by the hepatic system and offers the patient a more desirable route of adminis­tration than injection. Due to the limited area of the oral cavity, the delivery system itself is restricted in size, and hence potent compounds, such as proteins and peptides, are often more suited to such delivery systems.

The oral cavity can be divided into three distinct functional areas: the lining mucosa (buccal, sublingal, and soft palate), the masticatory mucosa (hard palate and gingiva), and the specialized mucosa (dorsal tongue). The thickness and keratinization of the tissue differs between these regions [79] and hence the permeability of each is unique [80]. The hard palate and gingiva are highly keratinized and subsequently offer limited permeability for drug delivery. The use of enhancers, however, has been shown to increase the perme­ability through keratinized tissues from bioadhesive platforms [81,82]. The majority of the work with systemic delivery systems using bioadhesives in the oral cavity has been con­centrated on the buccal (cheek) route of administration because of its large surface area and nonkeratinization. Bioadhesive buccal tablets or patches have been utilized as delivery systems. They are usually designed to be unidirectional in their delivery (i. e., delivering the drug from the side of the patch attached to the buccal mucosa and not to rest of the mouth). This is often accomplished by an impermeable backing facing the oral cavity. The bioadhesive of choice can then serve two purposes: as an adhesive keeping the delivery system in place and/or as a drug-containing matrix in which the compound diffuses from the matrix and permeates the mucosa into the general circulation.

When administered in a mucoadhesive tablet, similar to the tablet containing lido — caine above but with the addition of an oil base and the penetration enhancer glycocho — late, insulin has shown increased absorption through the oral mucosa [83]. Insulin blood levels, however, were significantly lower in comparison to systemic levels achieved by intramuscular injection. The reason for the low bioavailability could be due to poor tissue permeability, even with the enhancer. Mucoadhesive dosage forms have also been used for the treatment of cardiovascular disorders such as angina and hypertension [84-86]. When administered by an adhesive delivery system, nifedipine showed plateau drug levels after 8 h and was sustained there until removal of the delivery system. Another delivery system using nitroglycerin in a bioadhesive buccal tablet has also been shown to have a sustained effect.