Chitosan-coated alginate (CCA) nanoparticles for augmentation of topical antihistaminic activity of diphenhydramine: in-vitro optimization, skin histopathology and pharmacodynamic studies with in vitro/in vivo correlation.

OBJECTIVE: The aim of the present study was to formulate chitosan-coated alginate nanoparticles containing the drug diphenhydramine hydrochloride (DHH). SIGNIFICANCE: Diphenhydramine hydrochloride (DHH) is the prototype of H1-antihistaminic drugs. It is a lipophilic drug, that easily crosses the blood-brain barrier when taken orally causing decrements in alertness and performance. Multiple applications of topical drug products are required. Thus, drug incorporation in nanocarriers would increase the skin penetration powers increasing the drug efficacy. METHODS: Chitosan-coated alginate (CCA) nanoparticles were prepared via polyelectrolyte complex technique adopting 23 full factorial designs. Three factors, namely, alginate concentration, drug-to-alginate ratio and CaCl2 volume, each in two levels were studied. The prepared formulae were evaluated utilizing entrapment efficiency (EE), particle size (PS), polydispersity index (PDI), zeta potential (ZP) and in vitro release. The characterization process was then followed by optimization. RESULTS: At alginate conc. of 1%, drug to alginate ratio of 2:1 and CaCl2 volume of 4 mL, NP8 was chosen as a candidate formula. Histopathological examination on shaved rat dorsal skin disclosed the safety of NP8 with no signs of necrosis or even inflammation. The enhanced topical delivery of diphenhydramine hydrochloride enclosed in the developed nanoparticles was further proved by induction of allergic reaction using intradermal histamine injection. The results revealed the superior ability of NP8 to decrease the diameter of the formed wheal in comparison to the marketed DHH product. CONCLUSION: Thus, CCA nanoparticles are considered candidate nanocarriers for fortifying the topical antihistaminic activity of DHH.

Drotaverine Hydrochloride Superporous Hydrogel Hybrid System: a Gastroretentive Approach for Sustained Drug Delivery and Enhanced Viscoelasticity.

This study aims to prepare drotaverine hydrochloride superporous hydrogel hybrid systems (DSHH systems) to prolong its residence time in the stomach, provide extended release and reduce its frequency of administration. Drotaverine hydrochloride (DRH) is a spasmolytic drug that suffers from brief residence due to intestinal hypermotility during diarrheal episodes associated with gastrointestinal colics resulting in low bioavailability and repeated dosing. Eight DSHH systems were prepared using gas blowing technique. The prepared DSHH systems were evaluated regarding their morphology, incorporation efficiency, density, porosity, swelling ratio, viscoelastic property, erosion percentage and release kinetics. The FH8 formula containing equal proportion of chitosan (3%) /polyvinyl alcohol (3%) as strengthener and crosslinked with tripolyphosphate showed the highest incorporation efficiency (91.83 ± 1.33%), good swelling ratio (28.32 ± 3.15% after 24 h), optimum viscoelastic properties (60.19 ± 3.82 kPa) and sustained release profile (88.03 ± 2.15% after 24 h). A bioequivalence study was done to compare the bioavailability of the candidate formula versus Spasmocure®. Statistical analysis showed significant (P < 0.05) increase in bioavailability 2.7 folds with doubled Tmax (4 h) compared to the marketed product (2 h). These results declared that the superporous hydrogel hybrid systems could be a potential gastroretentive approach for the sustained delivery of drugs with short residence time with enhanced viscoelasticity.