Methods to simulate rubbing of topical formulation for in vitro skin permeation studies
Publication date: 15 March 2017 Source:International Journal of Pharmaceutics, Volume 519, Issues 1–2 Author(s): Hiep X. Nguyen, Ashana Puri, Ajay K. Banga Rubbing a topical formulation on skin is generally assumed to enhance drug penetration. The aim of this study was to demonstrate different techniques such as using glass rod, rheometer, and gloved finger for rubbing a 2% salicylic acid gel on skin and investigate their effect on in vitro permeation of salicylic acid through dermatomed porcine ear skin. The studies included evaluation of the gel’s rheological properties, gel distribution on skin surface, in vitro permeability, drug distribution in skin, skin extraction recovery, and mass balance. Rubbing with a gloved finger resulted in a uniform gel layer with a thickness of 49.61±15.33μm on the skin surface. No significant difference between the different test groups was observed in terms of the cumulative amount of drug that permeated in 24h (p> 0.05). Drug levels in stratum corneum, epidermis, and dermis were also analyzed. Rubbing with gloved finger delivered significantly higher amount of drug into the skin layers as compared to other test groups (p< 0.05). Amount of drug extracted from skin was reliably correlated to the actual drug levels in skin (R2 =0.99). Considering drug amounts in different compartments, mass balance ranged from 75.86±2.90% to 80.44±2.99%. Graphical abstract
CONCLUSION: Essential and dystonic vocal tremors responded differently to treatment. Dystonic vocal tremors responded significantly to treatment with botulinum toxin but not oral propranolol. Essential vocal tremors did not respond significantly to either treatment, perhaps due to the small number of patients, which is a limitation of this research.
CONCLUSION: Patients arrived very sick and displayed poor survival after deceased donor transplantation.
CONCLUSION: Except for the STOP-BANG questionnaire, subjective evaluation of sleepiness, sleep quality, perception of onset, and total sleep time are not important parameters for the diagnosis of obstructive sleep apnea, which reinforces the need for an active search for better management of these patients.
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