Preparation and stability testing of a hydrogel for topical analgesia

A stability and validation study of 1%w/w menthol in aqueous cream

In this study an analytical method for the determination of menthol in aqueous cream was developed, together with the complete validation of the production process and stability testing of 18 months' retained reference samples. Cream packed in 500ml plastic screw cap containers was tested and studied. Up to now there has only been a small scale (1.40kg) manual manufacture of 1%w/w menthol in aqueous cream without any formal quality control analysis and testing carried out on the product.

The purpose of this work was to enable large scale manufacture of the product, which would require development of an analytical method and validation of the mixing and filling processes. Stability testing of stored reference samples was carried out concurrently.

A stability-indicating, gas-liquid chromatographic method, with the use of an internal standard, was developed and validated for the product. Stability testing of samples stored at 25C ± 1C showed no significant degradation over 18 months. Validation of the manufacturing process by a sequential sampling technique showed the process to be satisfactory and workable at all stages.

The current formulation in use is 1%w/w menthol triturated directly into aqueous cream BP.

A comparison of the efficacy of topical application of Lignocaine Hydrochloride 5% gel and Bupivacaine Hydrochloride 5% gel for extraction of teeth

BACKGROUND

With the advancements in dentistry the treatments are done with high perfections and patient comfort. Noninvasive, methods reduce fear and anxiety of the patient on phobia of syringes and injections. Topical anesthesia satisfies all the above criteria.

AIM AND OBJECTIVE

Comparison of the efficacy of topical application of lignocaine hydrochloride 5% gel and bupivacaine hydrochloride 5% gel for extraction of teeth.

MATERIALS AND METHODS

Lignocaine hydrochloride 5% gel and bupivacaine hydrochloride 5% gel are prepared with carbopol (thickening agent). 510 extractions with lignocaine hydrochloride gel 5% and bupivacaine hydrochloride gel 5% in equal numbers was undertaken. Parameters of onset of anesthesia, peak effects, pain, and disappearance of numbness, local irritation, bleeding and periodontal status of teeth to be extracted were taken into consideration.

RESULTS

Onset and peak effect were faster with 5% lignocaine hydrochloride gel. 5% bupivacaine hydrochloride gel had longer duration of analgesia. Patients experienced more pain with bupivacaine. Grade 1 mobile posterior teeth were painful during extraction.

CONCLUSION

5% lignocaine hydrochloride gel is better than 5% bupivacaine hydrochloride gel as a topical anesthetic for extraction of grade II and grade III mobile teeth.

Three-dimensional axisymmetric flow-focusing device using stereolithography

This paper describes a three-dimensional microfluidic axisymmetric flow-focusing device (AFFD) fabricated using stereolithography. Using this method, we can fabricate AFFDs rapidly and automatically without cumbersome alignment needed in conventional methods. The AFFDs are able to be fabricated reproducibly with a micro-sized orifice of diameter around 250 mum. Using this device, we are able to produce monodisperse water-in-oil (W/O) droplets with a coefficient of variation (CV) of less than 4.5%, W/O droplets with encapsulated microbes (CV < 4.9%) and oil-in-water (O/W) droplets (CV < 3.2%) without any surface modifications. The diameter of these droplets range from 54 to 244 mum with respect to the flow rate ratio of the fluids used; these results are in good agreement with theoretical behavior. For applications of the AFFD, we demonstrate that these devices can be used to produce double emulsions and monodisperse hydrogel beads.

Preparing children for venepuncture. The effect of an integrated intervention on distress before and during venepuncture

Venepuncture for routine blood sampling is a very distressing experience for a considerable number of children. Not only do they express high levels of distress during venepuncture but also in anticipation of the procedure. Therefore, prevention or reduction of distress should focus on both phases of the procedure. To this end, three preparation elements were combined: local anaesthesia of the skin, provision of sensory and procedural information, and involvement of the parent. In order to test the effect of this integrated procedure on the distress reactions of young children before as well as during venepuncture, 31 children were randomly assigned to one of two conditions: preparation or no preparation. Independent raters, who were blind to group assignments, scored segments of the videotaped behaviour of the children, according to the Groninger Distress Scale. Prepared children displayed significantly less distress before and during venepuncture than not-prepared children, regardless of their gender, ethnical origin, age, injection history, and the tension of their parent.

Chitosan-EDTA conjugate: a novel polymer for topical gels

A recently developed chitosan-EDTA conjugate, neutralized with sodium hydroxide (NaChito-EDTA), has been tested for possible topical use. The technical properties and microbial stability of NaChito-EDTA have been compared with those of carmellose sodium (NaCMC), hydroxypropylmethylcellulose (HPMC), sodium polycarbophil (NaPCP) and sodium carbopol 980 (NaC980), well established gelatinizing agents. NaChito-EDTA forms stable, colourless, completely transparent hydrogels at a polymer concentration of 0.5%. Of the polymers tested the novel polymer had the lowest incompatibility with multivalent cations and with ethanol, and much the best swelling properties. After 28 days of incubation at room temperature the rates of growth of the complete bacterial spectrum occurring in demineralized water and of Escherichia coli, serving as model strain representative of gram-negative bacteria, were at least 2 log and 5.7 log, respectively, lower in NaChito-EDTA gels than in the other hydrogels. This antimicrobial activity of NaChito-EDTA can be explained by its highest binding affinity towards magnesium, which stabilizes the outer membrane of gram-negative bacteria. However, this antimicrobial effect is insufficient to guarantee microbial stability. Further results showed that the antimicrobially acting polypeptide nisin can be recommended as an alternative novel preservative for NaChito-EDTA gels, because its antimicrobial spectrum could also be increased towards gram-negative bacteria in combination with chelating excipients. NaChito-EDTA seems, therefore, to be a promising novel polymer for topically-used gels, with advantages over well established gelatinizing agents.