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Biomedical subjects

M J Groves

Publications and source records attributed to M J Groves.

At least 73 records · Page 4Linked to original sources
PubMed1984

The solubility of 17 beta-oestradiol in aqueous polyethylene glycol 400.

The solubility of 17 beta-oestradiol (E2) in aqueous solutions of polyethylene glycol (PEG) 400 has been measured at 35 degrees C. Up to 80% w/w PEG the solubility data conform to a log linear equation ln S = ln Sw + f sigma where S is the E2 concentration in the water/cosolvent mixture, Sw is E2 solubility in water, f is the weight fraction of PEG 400 and sigma is a parameter representing the solubilizing power of the cosolvent for the drug. Above 80% PEG the relationship becomes less convincing, with significant deviation from anticipated values. Reasons for these aberrations are discussed. It is suggested that conformational changes may be induced in the PEG by the addition of small quantities of water. Deviations noted for the melting point, viscosity and density data of PEG 400-water solutions may also confirm this suggestion.

Calorimetry, Differential Scanning↗
PubMed1975

The evaluation of a column-type dissolution apparatus.

An improved column-type dissolution apparatus is described. The column of the apparatus is built from standard screw-cap connected "Sovirel" glass tubes which should enable inter-apparatus variability to be reduced. The main problem with this type of device is the build up to back pressure as fragments from the disintegrating solid dosage form progressively block the filtration system, itself necessary to stop the solution process and present the solution for analysis. A simple type of light-activated switch is therefore used which works across the indicator float of a flow meter to drive a motor connected to a needle valve. As the float falls the motor is switched on to open the valve and increase the flow rate until the float rises again and causes the motor to switch off. Observation on the dissolution characteristic of dyed lactose tablets and the injection of dye solutions into the flowing stream of liquid around tablets showed that there was back-flow of solution at Reynolds Numbers below 10 but visible instability to flow at Re greater than 100. Over a range of flow rates between Re 10-70 the mass of drug released at a given time was a direct function of flow rate for a film coated product but an inverse function for a sugar coated tablet. The results are discussed in relation to the main problems which can be experienced with a column-type dissolution apparatus.

Evaluation Studies as Topic↗