Abstract:
Introduction. A very important pharmaceutical parameter in exercising a maximum
pharmacological effect is the bi speed of disposal of the active substance by a pharmaceutical form, its absorption in the body,
its transport to the site of action and its biological response.
Aim of the study. Advanced bibliographic study on the diversity of methods used in the study
of bioavailability of ear drops.
Materials and methods. 87 abstracts and scientific articles from the Cochrane Electronic
Library, MEDLINE databases, CAB Abstracts © and SciSearch © The Thomson Corporation.
Results. The bibliographic evaluation of the sources studied has highlighted the importance of
the basic physico-chemical characteristics of the drug substances incorporated in the
pharmaceutical form, which directly influence the bioavailability. For example: drugs with
high molecular weight or high electrical charge cross the blood-brain barrier (inner ear
membrane) with passive difficulty, as well as protein-binding substances, while high
liposolubility of drug substances facilitates passage. It has been established that there are
several methods used to investigate the bioavailability of active principles from ear drops, using
Franz diffusion vertical cells. Animal skin is often recommended for preliminary evaluations
of new formulations as a membrane for yield. Animal models used to replace human skin are
domestic pigs, rats, mice, guinea pigs and snakes. Thus, 26% of the evaluated sources propose
the use of the skin of newborn pigs. In most articles (68%) it is proposed to use the skin on the
inner side of the pig's ear, as results are comparable to those obtained on human skin due to
similar thickness, vascular anatomy and arrangement of collagen fibers in the dermis of the ear,
as well as due to the identical glycosphingolipid and ceramide content. The bioavailability
assessment is done by determining the concentration of the substances (usually by
chromatographic or spectral methods) at equal intervals in the yield medium.
Conclusions. Bioavailability is extremely important for the preformulation and drug
formulation process, and the correct selection of the in vitro determination method facilitates
the correlation of results with those obtained in vivo.oavailability of medicines, which represents the quantity and
Description:
Department of Pharmaceutical and
Toxicological Chemistry, Nicolae Testemitanu State University of Medicine and Pharmacy,
Chisinau, Republic of Moldova, The 8th International Medical Congress for Students and Young Doctors, September 24-26, 2020
