Nasal drug administration has been used as an alternative route for the systemic availability of drugs restricted to intravenous administration. This is due to the large surface area, porous endothelial membrane, high total blood flow, the avoidance of first-pass metabolism, and ready accessibility. The nasal administration of drugs, including numerous compound, peptide and protein drugs, for systemic medication has been widely investigated in recent years. Drugs are cleared rapidly from the nasal cavity after intranasal administration, resulting in rapid systemic drug absorption. Several approaches are here discussed for increasing the residence time of drug formulations in the nasal cavity, resulting in improved nasal drug absorption. The article highlights the importance and advantages of the drug delivery systems applied via the nasal route, which have bioadhesive properties. Bioadhesive, or more appropriately, mucoadhesive systems have been prepared for both oral and peroral administration in the past. The nasal mucosa presents an ideal site for bioadhesive drug delivery systems. In this review we discuss the effects of microspheres and other bioadhesive drug delivery systems on nasal drug absorption. Drug delivery systems, such as microspheres, liposomes and gels have been demonstrated to have good bioadhesive characteristics and that swell easily when in contact with the nasal mucosa. These drug delivery systems have the ability to control the rate of drug clearance from the nasal cavity as well as protect the drug from enzymatic degradation in nasal secretions. The mechanisms and effectiveness of these drug delivery systems are described in order to guide the development of specific and effective therapies for the future development of peptide preparations and other drugs that otherwise should be administered parenterally. As a consequence, bioavailability and residence time of the drugs that are administered via the nasal route can be increased by bioadhesive drug delivery systems. Although the majority of this work involving the use of microspheres, liposomes and gels is limited to the delivery of macromolecules (e.g., insulin and growth hormone), the general principles involved could be applied to other drug candidates. It must be emphasized that many drugs can be absorbed well if the contact time between formulation and the nasal mucosa is optimized.

Phthalocyanines (Pcs) are a class of photosensitizers (PSs) with a strong tendency to aggregate in aqueous environment, which has a negative influence on their photosensitizing ability in photodynamic therapy. Pcs with either peripheral or axial solketal substituents, that is, ZnPc(sol) 8 and Si(sol) 2 Pc, respectively, were synthesized and their tendency to aggregate as well as their photodynamic properties in 14C and B16F10 cell lines were evaluated. The results were compared to more hydrophilic silicon Pcs, that is, Si(PEG750) 2 Pc and Pc4. The order of cellular uptake was Pc4 > ZnPc(sol) 8 > Si(PEG750) 2 Pc > Si(sol 2 )Pc. In contrast, Si(sol 2 )Pc showed the highest photocytotoxicity, while ZnPc(sol) 8 did not show any photocytotoxicity up to a concentration of 10 µM in both cell types. UV/vis spectroscopy showed that Si(sol) 2 Pc is less prone to aggregation than ZnPc(sol) 8 , which can explain the lack of photoactivity of the latter. Si(sol) 2 Pc was predominantly located in lipid droplets, whereas Si(PEG750) 2 Pc was homogeneously distributed in the cytosol, which is probably the main cause of their difference in photoactivity. The very high photodynamic efficacy of Si(sol) 2 Pc makes this PS an interesting candidate for future studies.

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The use of nebulised magnesium sulphate in moderate asthma exacerbation as adjuvant treatment showed no benefit to standard treatment in our study.