ABSTRACT
Objectives: Patients undergoing surgery involving general anesthesia often suffer from hypothermia, which is associated with various complications. External heating and warming are used to combat hypothermia throughout surgery; however their effectiveness is often limited. In this study we investigated a unique approach utilizing a natural physiological mechanism; protective cutaneous vasoconstriction for reducing peri-anesthetic hypothermia. The concept is based on the dermal application of a cream with vasoconstrictive alpha adrenergic agonist properties designed for this purpose; “thermal cream” (TC). Topical application of the cream was tested in a rodent model. The aim of the present study was to test the efficacy of a topical vasoconstrictive application in reducing peri-anesthetic hypothermia. Materials and Methods: Adult Wistar rats were divided into two experimental arms: application of thermal cream was compared to application of a base cream without any active compound (control) under the same conditions. The rats were exposed to an ambient temperature of 21ºC. Their skin and core temperatures were measured and compared before, during and after anesthesia. Results: The rats underwent rapid hypothermia immediately after the induction of anesthesia. The rats treated with thermal cream had a significantly higher core body temperature than the controls throughout the entire anesthetic period. This difference was even greater when the cream had been applied before the animal underwent anesthesia. Conclusions: The thermal cream was effective in attenuating peri-anesthetic-induced hypothermia in a rodent model. It was easy to apply with no immediate mortality or other major adverse events.
ABSTRACT
Aqueous extracts of Roselle or Hibiscus sabdariffa L calyces have characteristic intense red colouration due to the presence of anthocyanins which could be utilised as colouring agent in pharmaceutical products. The aim of the current study was to evaluate the potential of aqueous extract of H. sabdariffa calyces as a colouring agent in three pediatric oral pharmaceutical formulations. The colour value of H. sabdariffa calyx extract was determined colorimetrically at λmax 540 nm to be within the BP range of ≥ 0.25. The colour value of H. sabdariffa (0.26) was lower than that of amaranth (0.46), a synthetic commercial pharmaceutical colourant. H. sabdariffa calyx extract retained its colour value within the BP standard for up to six months. The aqueous extract of H. sabdariffa calyces at 33 % w/v was used as colouring agent in paracetamol syrup, diphenhydramine syrup and pediatric cough linctus and the colour stability of the formulations against temperature, light and pH were determined. H. sabdariffa calyx extract was less stable than amaranth to temperature, light and pH when used as a colouring agent. H. sabdariffa calyx extract at 33 % w/v has potential as a colouring agent in pharmaceutical formulations when buffered at pH 5.0, packaged in amber bottles and stored at low temperatures (26-37 °C).