Prilling of API/fatty acid suspensions: Processability and characterisation.

Current study evaluated the processability and characteristics of prills made of an active pharmaceutical ingredient/fatty acid (API/FA) suspension instead of previously studied API/FA solutions to enlarge the application field of prilling. Metformin hydrochloride (MET) and paracetamol (PAR) were used as model APIs while both the effect of drug load (10-40%) and FA chain length (C14-C22) were evaluated. API/FA suspensions were processable on lab-scale prilling equipment without thermal degradation, nozzle obstruction or sedimentation in function of processing time. The collected prills were spherical (AR ≥ 0.898) with a smooth surface (sphericity ≥ 0.914) and a particle size of ±2.3 mm and 2.4 mm for MET and PAR prills, respectively, independent of drug load and/or FA chain length. In vitro drug release evaluation revealed a faster drug release at higher drug load, higher API water solubility and shorter FA chain length. Solid state characterisation via XRD and Raman spectroscopy showed that API and FA crystallinity was maintained after thermal processing via prilling and during storage. Evaluation of the similarity factor indicated a stable drug release (f2 > 50) from MET and PAR prills after 6 months storage at 25 °C or 40 °C.

Effect of ultrasound and heat on percutaneous absorption of l-ascorbic acid: human in vitro studies on Franz cell and Petri dish systems.

OBJECTIVE: Percutaneous absorption of l-ascorbic acid (LAA) is limited due to its high hydrophilicity and low stability. Here, we investigated the effect of post-dosing sonophoresis (329 kHz, 20 mW cm-2 ) and heat (36°C) on transdermal delivery of LAA. METHODS: Ultrasound/heat, heat and control treatments were applied on skin surface for 2 and 5 min after topical application of C14-labelled LAA aqueous solution. After 15 min post-exposure, radioactivity was measured in tape-striped stratum corneum (TS-SC), epidermis, dermis and receptor fluid. As Franz diffusion cell model may have different acoustic response than in vivo human tissues, a novel Petri dish model was developed and compared with Franz cell model on the effects of ultrasound/heat treatment on the skin permeability. RESULTS: Five-min ultrasound/heat treatment significantly accelerated skin absorption/penetration of LAA; 2-min treatment showed no enhancement effect on Franz diffusion cell model at the end of experiment. The use of Petri dish model significantly increased LAA concentrations in epidermis after 5 min of ultrasound/heat treatment, compared to the results of Franz cell model. CONCLUSION: Combination of ultrasound (329 kHz, 20 mW cm-2 ) and heat (36°C) significantly enhanced LAA transdermal penetration, when the time of treatment was sufficient (5 min). As Petri dish model was designed to simulate acoustic respond of dense human tissue to ultrasound, the difference between Franz cell and Petri dish models suggests that the enhancement effect of ultrasound/heat on skin penetration in vivo may be greater than that determined on in vitro Franz cell model.

The effect of resilient layer and occlusal reactive complete dentures on the residual alveolar ridge.

A technique for making resilient layer and occlusal reactive dentures was proposed. A radiographic and clinical evaluation of the effect of these dentures on the residual ridges of 17 subjects was done. The results showed that the rate of ridge reduction with these dentures was significantly less than that with conventional dentures. Therefore, the resilient layer principle is a promising clinical modality.