The influence of cetomacrogol ointment processing on structure: A definitive screening design.

Batch-to-batch variability is a challenge for the industrial scale production of ointments. Therefore the current investigation focussed on identifying and understanding critical process parameters (CPPs) for cetomacrogol ointment. This was evaluated using a definitive screening design (DSD) approach in which fourteen batches were produced under predefined and controlled conditions using the following variables: addition of SiO2 nanoparticles, mixing speed, cooling rate, heating temperature, container filling temperature and isothermal mixing at the filling temperature. Ointment structure was evaluated using a number of rheological parameters. One of these parameters, yield stress was found to be strongly influenced by filling temperature and mixing speed (p=0.0065 and p=0.0013 respectively). Both significantly affect ointment structure and they also have a significant interaction (p<0.05). Understanding the ointment production process can help in defining a processing window to produce ointment of constant quality.

Excitatory and depressant effects of dieldrin and aldrin-transdiol in the spinal cord of the toad (Xenopus laevis).

An investigation was made into the action of the insecticide dieldrin and one of its metabolites, aldrin-transdio, on the isolated spinal cord of the toad, Xenopus laevis. Conventional electrophysiological techniques were used for stimulating and recording of dorsal and ventral spinal roots. An augmentation of polysynaptic reflex activity along with a marked reduction of orthodromic postsynaptic inhibition could be demonstrated in preparations isolated from dieldrin-poisoned animals. However, application of dieldrin to the isolated spinal cord failed to produce any significant effect. Application of aldrin-transdiol, on the other hand, caused a potentiation of spinal reflex activity and an increase in spontaneous activity of ventral and dorsal roots. Aldrin-transdiol also produced a marked reduction of spinal inhibitory mechanisms. The excitatory effects of aldrin-transdiol were followed by a strong depressant action on spinal excitability.