Biomedical subjects

Adriana Memoli

Publications and source records attributed to Adriana Memoli.

3 recordsLinked to original sources

PubMed2004

Diclofenac sodium multisource prolonged release tablets--a comparative study on the dissolution profiles.

The aim of this work was to compare the dissolution behaviour of six diclofenac sodium prolonged release tablets of different brands obtained from the national market. The formulations contain the same amount of drug substance but different types and/or amount of excipients. The influence of these differences in formulation on the release characteristics of the dosage forms was evaluated on the European Pharmacopoeia apparatus 2 (paddle) employing eight different dissolution media in the pH range 1.2-8. Friability and hardness were tested too according to the European Pharmacopoeia. Dissolution profiles obtained from the studied formulations showed that the release characteristics vary considerably among different manufacturers and that even identical formulations show rather dissimilar release profiles in all the studied media. Use of both SIF without pancreatin and SIF without pancreatin containing 1% (w/v) Tween 20 resulted in strong discrimination among products. A correlation between friability and hardness and in vitro dissolution was evidenced for two formulations having identical excipient composition.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2004

Effects of insulin-induced acute hypoglycemia and normoglycemic hyperinsulinemia on the retinal uptake and ocular metabolism of glucose in rabbits.

Glucose is the principal metabolic substrate for the retina in mammals, being essential for maintaining the functional activity of the retina; it can be supplied to the tissue by both vitreous humor and blood. Yet, the impact of hypoglycemia on retinal glucose metabolism has been poorly investigated. We have therefore studied the effects of acute insulin-induced hypoglycemia on the glucose uptake and metabolism in the retina, by analyzing the hypoglycemia-induced changes in the ocular distribution and metabolic fate of [3H]-2-deoxy-D-glucose (2-DG) and [14C]-D-glucose, both injected in the vitreous body. Rabbits were rendered hypoglycemic by subcutaneous injection of insulin (0.8 and 1.2 IU/kg). Insulin-induced hypoglycemia increased both retinal [3H]-radioactivity levels and retina to vitreous humor ratio of [3H]-radioactivity levels ([3H]-[R/VH]). Radio-chromatography showed that hypoglycemia did not induce any change in the retinal conversion of 2-DG to 2-DG-6-phosphate, but increased the conversion of [14C]-D-glucose to [14C]-lactate. Normoglycemic hyperinsulinemia caused no change in either retinal [3H]-radioactivity levels or [3H]-[R/VH] while decreasing retinal [14C]-radioactivity levels and retina to vitreous ratios of 14C-radioactivity levels. These results indicate that acute hypoglycemia increases the uptake rate of glucose by the retina and suggest that normoglycemic hyperinsulinemia may decrease retinal lactate, possibly stimulating its removal from the retina.

Animals↗

PubMed2002

A comparison between different immobilised glucoseoxidase-based electrodes.

Biosensors obtained by immobilising glucose oxidase 'unentrapped' and 'entrapped in liposomes', both with a classical H2O2 amperometric electrode and with screen-printed electrochemical sensor, were compared. Electrode response, linearity range and the influence of some parameters as phospholipid nature, temperature and measurement techniques were investigated. Experimental results showed that, while with the unentrapped enzyme the output current is linear only up to about 4 mM glucose concentration, the linearity range increases up to about 20 mM using enzyme-loaded liposomes; however the low permeability of the lipid bilayer decreases the electrode sensitivity to very low values (200 nA/M for palmitoylolelyl phosphatidylcholine liposomes). The approach with screen-printed sensors showed a better performance and gave biosensors with higher sensitivity (about 14500 nA/mM). A mathematical model, useful to compare the behaviour of the different analytical systems and to design electrodes with the required properties, was also proposed.

Biosensing Techniques↗