RESUMO
The technological processing of the benzodiazepine derivatives chlordiazepoxide, medazepam, diazepam, nitrazepam and clonazepam with methyl cellulose (mc) and hydroxyethylcellulose--especially physical mixtures and evaporates--led to an improved dissolution of the problem drugs. The effect of the adjuvants is remarkable in the initial phase of the dissolution and very distinctive at the end of the experiment. Obviously there is no relation between saturation solubility and dissolution. Only with nitrazepam and clonazepam, but less clearly with medazepam, an increase of solubility by the mc-trituration was observed. Studies of the binding showed a concentration and temperature dependent interaction of the benzodiazepines diazepam, clonazepam, medazepam and nitrazepam, to mc. As X-ray diffraction and differential thermoanalysis gave no interpretation for the improved dissolution behaviour of drug/adjuvant preparations, it is assumed that a high distribution of the drug particles in the dissolution medium by the preceding treatment with cellulose ether is the main reason for the increase of the dissolution rate.
Assuntos
Ansiolíticos/análise , Celulose , Química Farmacêutica , Diazepam/análise , Éteres , Excipientes , Cinética , Solubilidade , Termodinâmica , ViscosidadeRESUMO
We report an analysis of the nuclear dependence of the yield of Drell-Yan dimuons from the 800 GeV/c proton bombardment of 2H, C, Ca, Fe, and W targets. Employing a new formulation of the Drell-Yan process in the rest frame of the nucleus, this analysis examines the effect of initial-state energy loss and shadowing on the nuclear-dependence ratios versus the incident proton's momentum fraction and dimuon effective mass. The resulting energy loss per unit path length is -dE/dz = 2.32+/-0.52+/-0.5 GeV/fm. This is the first observation of a nonzero energy loss of partons traveling in a nuclear environment.