[Do physicians know the cost of the treatments and tests they prescribe?]. / Conocen los médicos el coste de los tratamientos y pruebas que solicitan?

OBJECTIVE: To determine the degree of knowledge among physicians regarding the cost of diagnostic tests and commonly used drugs. INDIVIDUALS AND METHODS: An interview was obtained with a representative sample of 164 physicians from a total of 338 (accuracy +/- 3.55), distributed in interns/residents (n:119) and staff members (n:45) from the divisions of Surgery (n:81) and Medicine (n:83) at Hospital Clinic i Provincial, Barcelona. The questionnaire included 15 questions, 10 regarding drugs and 5 diagnostic tests, with 5 possible answers. An arbitrary scoring system was used (correct answer: 5 points; approximate; 3 points; mistake: 1 point) and the percentage of right answers (correct and approximate answers) was also evaluated versus mistakes. The Student "t" test, the analysis of variance and the chi 2 test were used to compare the results. RESULTS: The overall score reached was 2.72 +/- 0.41. Differences between residents vs staff and medicine vs surgery were not significant. The score in questions regarding diagnostic tests was significantly higher than that obtained for drug cost among all group. The percentages of right answers (correct and approximate answers) were 58.8%-61.7% (drugs) and 58.3-60.8% (tests), with no differences among groups. Differences regarding year of residence were also not significant. CONCLUSIONS: The knowledge degree on costs of some drugs and diagnostic tests among physicians is deficient. It is necessary to find standards that contribute to increase the level of information regarding costs derived from the health care delivery process among health care professionals.

Permeation mechanisms through artificial lipoidal membranes and effects of synthetic surfactants on xenobiotic permeability.

Through the use of permeation/lipophilicity correlations, the mechanisms of permeation of selected test compounds across artificial lipoidal membranes of the polysiloxane type, in the absence and in the presence of a nonionic surfactant (Polysorbate 80), are investigated, in order to design "in vitro" conditions and features suitable for reproducing "in vivo" intestinal absorption tests, as well as to validate some conclusions arising from "in situ" rat gut experiments about the effects of the synthetic surfactants on drug and xenobiotic absorption processes. Six 4-alkylanilines showing a perfect homology were used as test compounds. The reported results clearly show that the in situ biophysical absorption (diffusion) models are completely reproduced by in vitro tests, provided that perfect sink conditions are achieved. Further selection of artificial membrane polarity should be necessary, however, in order to exactly equalize in vitro and in situ permeation rates. As far as the synthetic surfactant action on permeability is concerned, our conclusions are similar to those drawn from in situ studies, except that the effect of the surfactant on membrane polarity is much smaller and the micelle-solubilizing effect somewhat larger. The disruption of the aqueous stagnant diffusion layers adjacent to the membranes by the surfactant has been conclusively demonstrated. A clear first-element deviation for aniline, which prevents its inclusion as a term of the tested series, has been observed; this feature should be borne in mind whenever any in vivo/in vitro correlation has to be established.

Absorption mechanisms of secondary aliphatic amines in rat colon and small intestine.

This study is intended to be a further and conclusive validation of the bihyperbolic model equation proposed by Plá-Delfina and Moreno to describe passive intestinal absorption mechanisms through the analysis of absorption-lipophilicity correlations for homologous series of xenobiotics and drugs. Secondary aliphatic amines, largely differing from previously tested substances, were selected as model compounds. Evidence is given which demonstrates that a minimum lipophilicity value exists for absorption in small intestine, instead of a maximum, as probabilistic theories predict. Moreover, bihyperbolic equation provides an excellent fit, with AIC figures up to -29. Aqueous pore absorption was small, presumably due to ionic interactions with pore charges (kp approximately 1.0 h-1), whereas membrane penetration was highly lucrative (km approximately 7.4 h-1), thus indicating that some part of the lipophilic ionic species is capable of penetrating "per se" the lipoidal membrane. As model predicts, bihyperbolic equation collapses to monohyperbolic for colonic absorption, where AIC figures up to -39 were found, with a km value of about 4.0 h-1. Membrane absorption efficiency was, surprisingly, similar in colon and small intestine for the tested solutes; it was attributed to the basic character of the compounds associated with working pH and ion absorption. This latter effect would deserve further investigation in oral sustained-release medication with basic drugs having similar pKa values.