Acta pharmaceutica Nordica最新文献

Disodium cromoglycate particles were labelled with 99mTc by spray-drying technique. The in vitro dissolution profile as well as the leakage of radioactivity from the drug particles were determined using a through-flow cell method. The radioactive drug particles were mixed with a lactose carrier and inhaled from a dry powder device by five healthy volunteers. The removal of the inhaled drug particles from the lungs was evaluated by a gamma camera. A close relationship between the dissolution of the drug as such and the leakage of radioactivity was noted. Gamma scintigraphy indicated a biphasic exponential removal of radioactivity from the lung region. The slow component with the halftime of about 55 min was mainly due to the dissolution of drug particles in the lungs. The halftime of the fast component describing mucociliary clearance was less than 10 min. This process was the dominating one for the removal of the drug from the lungs. The experiment thus showed that the main fraction of the inhaled dose was deposited in the tracheobronchial region. Accordingly, only a small portion of the dose initially deposited in the lung can be absorbed and induce a therapeutic effect.

The kinetics and mechanism of hydrolysis of 1,3-benzoxazine-2,4-dione and its N-methyl and N-benzoyl derivatives were studied in aqueous solution to provide basic information on the reactivity of the benzoxazinedione structure and to assess the potential of unsubstituted 1,3-benzoxazine-2,4-dione as a prodrug for salicylamide. The compounds were found to hydrolyze quantitatively to the parent salicylamide. The pH-rate profiles obtained at pH 1-11 were accounted for by a spontaneous or water-catalyzed reaction which predominated at pH 1-4 and a hydroxide ion-catalyzed reaction. The rates of hydrolysis were catalyzed slightly in the presence of human plasma and rat liver homogenate, the exception being the N-benzoyl derivative which was hydrolyzed very fast in plasma solutions to N-benzoylsalicylamide. The aqueous solubility and lipophilicity characteristics of 1,3-benzoxazine-2,4-dione were determined. The results obtained suggest that the latter may function as a prodrug for salicylamide with the potential of depressing the extensive first-pass metabolism of salicylamide following oral or rectal administration.

A labile intermediate in the photolytic rearrangement of the antibacterial drug tinidazole was isolated after photolysis of the drug in acetone. The intermediate was identified through structural studies as 1-[2-(ethylsulphonyl)ethyl]-2-methyl-4-hydroxyimino-5-oxo-im idazole. A second product was identified as N-[2-(ethylsulphonyl)ethyl]-5-methyl-1,2,4-oxadiazole-3-carboxa mid e. A different compound, N-[2-(ethylsulphonyl)ethyl]-oxamide, crystallized in an ethanolic solution of tinidazole exposed for four months on a sunny window sill. Tinidazole was hydrolyzed completely to 2-methyl-5(4)-nitroimidazole when refluxed in 0.1 M NaOH solution, and was converted to 4-nitro isomer when refluxed in water with a catalytic amount of base.

Various N-substituted 4-(aminomethyl)benzoate diesters of ganciclovir were synthesized and evaluated as prodrug forms with the aim of improving the delivery characteristics of ganciclovir. The esters were hydrolyzed enzymatically by human plasma to the parent drug, the hydrolysis proceeding through formation of the corresponding monoester. The nature of the amino substituents had a marked influence on the rate of enzymatic hydrolysis, the most enzymatically labile ester being the 4-(morpholinomethyl)benzoate derivative. All esters were more lipophilic than ganciclovir in terms of octanol-pH 7.4 buffer partition coefficients. These properties combined with good aqueous solubility and high chemical stability in weakly acidic solutions make the N-substituted 4-(aminomethyl)benzoate diesters a promising prodrug type for ganciclovir to enhance its delivery characteristics for e.g. parenteral administration.

The loss of nitroglycerin (GTN) during passage through a polyvinyl chloride (PVC) or polyethylene (PE) infusion set was investigated. The GTN concentration had no influence on the GTN loss in the PVC set. The study confirmed reports in the literature that the greatest loss of GTN occurs at the slowest rate of infusion. Interestingly, the lowest concentration of GTN is seen when the volume equivalent to the capacity of the infusion set has passed through the set. When we simulated the procedure recommended by the health authorities in Norway and Sweden, we observed a loss of up to 70% during infusion through the PVC set in the first 30 minutes, which decreased to 30% over the next seven hours. The loss from the PE set did not exceed 15% over eight hours.

Chewing gum and lozenges were evaluated as delivery systems for noscapine with the aim of developing improved antitussive preparations. The formulations studied were prepared with both the water-soluble hydrochloride salt of noscapine and with the poorly soluble embonate salt and noscapine free base. The release characteristics of the preparations were evaluated both in vitro and in vivo, and their taste properties examined. Only the formulations containing noscapine base were without any appreciable taste. Chewing gum containing this compound showed, however, a low level of drug release both in vitro and in vivo and is therefore not a suitable dosage form. Only a lozenge formulation containing noscapine base fulfilled the requirements of taste acceptability and adequate release properties.

The synthesis of two series of 1-(N-methylanilinoethyl)indoles is reported. The first arises from the N-alkylation of indole-3-acetic acid or its methylester, while the second was prepared by means of the Witting reaction on the appropriate aldehyde. The compounds were tested in mice (hot plate test and phenyl-p-benzoquinone induced writhing test) for their analgesic activity. None of the compounds was significantly active in the hot plate test. However, N-methylanilinoethyl 1-(N-methylanilinoethyl)-3-indolylacetate (7) was the most active one in the phenyl-p-benzoquinone induced writhing test, which indicates that 7 has a peripheral analgesic effect.