Deceased Donor Organs: What Can Be Done to Raise Donation Rates Using Evidence From Malaysia?

Organ donation rates have continued to fall seriously short of needs worldwide, with the lowest rates recorded among developing economies. This study seeks to analyze evidence from a developing economy to explore the usefulness of social psychological theory to solve the problem. The study deployed a large survey (n = 10 412) using a convenience sampling procedure targeted at increasing the number of Malaysians registered with the Ministry of Health, Malaysia who are willing to donate organs upon death. Structural equation modeling was deployed to estimate simultaneously the relative influence of cognitive and noncognitive variables on willingness to donate deceased organs. The cognitive factors of donation perception, socioeconomic status and financial incentives, and the noncognitive factors of demography and fear showed a high statistically significant (1%) relationship with willingness to donate organs after death. While financial incentives were significant, cash rewards showed the least impact. Donation perception showed the highest impact, which shows that the development of effective pedagogic programs with simultaneous improvements to the quality of services provided by medical personnel engaged in retrieving and transplanting deceased donor organs can help raise organ donation rates.

Dissolution-controlled transport from dispersed matrixes.

A simplified mathematical model for dissolution-controlled transport from dispersed matrixes is presented. Analytical solutions have been obtained previously when solute diffusion totally controls the transport process. However, when solute dissolution offers the limiting resistance to mass transport, the solution reduces to a form where the mass released varies directly with time. Experimental release rates of a drug from a dispersed polymeric matrix into water were measured for a range of drug particle sizes in order to test the applicability of the proposed model; the agreement between theory and experimental is good.

Heterogeneous model of drug release from polymeric matrix.

The kinetics of drug release from a polymeric matrix originally proposed by Higuchi were extended for the case of high drug loading (relative to the solubility of the drug in the polymer). The model of a granular matrix in which an effective porosity and tortuosity are assumed to modify the normal Higuchi kinetics is reviewed. A new model, which allows the prediction of the kinetics of drug release from properties of the polymer and drug, is based on the assumption that the permeability of the dispersed matrix is a function of drug loading.

Pharmacokinetics of drug permeation through human skin.

Based on sorption and permeation characteristics of scopolamine in human skin in vitro and drug elimination kinetics obtained from pharmacokinetic studies, a mathematical model was developed for estimating and optimizing the temporal pattern of scopolamine delivery from a transdermal therapeutic system through human skin in vivo. Experimentally measured scopolamine delivery in vivo conformed to this model.

Factors influencing the percutaneous absorption of drugs.

The skin is the most readily accessible organ of the human body; only a fraction of a millimeter separates its surface from the underlying capillary network. Yet, skin protects superbly against damage by micro- and macro-molecular entities, as well as against uncontrolled loss of vital biological substances, by virtue of its astonishingly low permeability to such substances. We have reexamined and attempted to reconcile the barrier characteristics of skin in terms not only of its composition and microstructure, but also of present understanding of membrane permeability and permselectivity. The principal barrier to percutaneous transport is localized within the stratum corneum. We have developed a mathematical model of this tissue as a two-phase protein-lipid heterogeneous membrane, which correlates the permeability of the membrane to a specific penetrant with the water solubility of the penetrant and with its lipid-protein partition coefficient. We have also found that a simplistic model of the sorption process, which invokes the coexistence of dissolved and mobile sorbed molecules in equilibrium with site-bound and immobile molecules within the membrane, accurately correlates experimental sorption data and transient transport measurements. The interstitial lipid phase of the stratum corneum is the cause of the exceedingly low, apparent diffusivity of drugs (e.g. scopolamine) and, in this regard, acts as the principal permeation barrier, whereas the drug sorbed by the stratum corneum is localized predominantly within the protein phase of the tissue. We have also found that the effects of the permeation adjuvant, dimethyl sulfoxide, on skin permeability are entirely consistent with accepted sorption-diffusion models of membrane transport, when changes in penetrant activity with changes in solvent composition and tissue microstructure induced by osmotic shock are properly allowed for.