In-vivo therapeutic efficacy in experimental murine mycoses of a new formulation of deoxycholate-amphotericin B obtained by mild heating.
(1/2621)
Heat-induced 'superaggregation' of deoxycholate-amphotericin B (AmB-DOC, Fungizone) was shown previously to reduce the in-vitro toxicity of this antifungal agent. We compared AmB-DOC with the formulation obtained by heating the commercial form (Fungizone, Bristol Myers Squibb, Paris, France) for 20 min at 70 degrees C, in the treatment of murine infections. An improvement of antifungal activity was obtained with heated AmB-DOC formulations due to a lower toxicity which allowed the administration of higher drug doses than those achievable with the commercial preparation. Single intravenous injections of heated AmB-DOC solutions were demonstrated to be two-fold less toxic than unheated ones to healthy mice. For mice infected with Candida albicans, the maximum tolerated dose was higher with heated than with unheated AmB-DOC solutions. In the model of murine candidiasis, following a single dose of heated AmB-DOC 0.5 mg/kg, 85% of mice survived for 3 weeks, whereas at this dose the immediate toxicity of the standard formulation in infected mice restricted the therapeutic efficacy to 25% survival. Both formulations were equally effective in increasing the survival time for murine cryptococcal pneumonia and meningoencephalitis. Injection of heated AmB-DOC solutions at a dose two-fold higher than the maximal tolerated dose observed with the unheated preparation (1.2 mg/kg) increased the survival time by a factor of 1.4 in cryptococcal meningoencephalitis. These results indicate that mild heat treatment of AmB-DOC solutions could provide a simple and economical method to improve the therapeutic index of this antifungal agent by reducing its toxicity on mammalian cells. (+info)
A study of local anaesthetics. Part 148. Influence of auxiliary substances on the surface tension, distribution coefficient and pharmaceutical availability from solutions of the potential drug VII.
(2/2621)
The influence of auxiliary substances of the polyol group (glycerol, propylene glycol, sorbitol) and of their concentration (5, 10, 15 and 20% by weight) upon surface tension, distribution coefficient and pharmaceutical availability from solutions of the potential drug VII, viz., N-[2-(2-propoxyphenylcarbamoyloxy)-ethyl] piperidinium chloride was studied. The substances were applied as hydrogel humectants. It was found that their influence on the surface tension, distribution coefficient and pharmaceutical availability from solutions of the potential drug VII depended on the type as well as concentration of the auxiliary substance. From the viewpoints of use in formulations of the drug form, sorbitol used at 5 and 10% concentrations represented the optimum. (+info)
Comparison of immunity generated by nucleic acid-, MF59-, and ISCOM-formulated human immunodeficiency virus type 1 vaccines in Rhesus macaques: evidence for viral clearance.
(3/2621)
The kinetics of T-helper immune responses generated in 16 mature outbred rhesus monkeys (Macaca mulatta) within a 10-month period by three different human immunodeficiency virus type 1 (HIV-1) vaccine strategies were compared. Immune responses to monomeric recombinant gp120SF2 (rgp120) when the protein was expressed in vivo by DNA immunization or when it was delivered as a subunit protein vaccine formulated either with the MF59 adjuvant or by incorporation into immune-stimulating complexes (ISCOMs) were compared. Virus-neutralizing antibodies (NA) against HIV-1SF2 reached similar titers in the two rgp120SF2 protein-immunized groups, but the responses showed different kinetics, while NA were delayed and their levels were low in the DNA-immunized animals. Antigen-specific gamma interferon (IFN-gamma) T-helper (type 1-like) responses were detected in the DNA-immunized group, but only after the fourth immunization, and the rgp120/MF59 group generated both IFN-gamma and interleukin-4 (IL-4) (type 2-like) responses that appeared after the third immunization. In contrast, rgp120/ISCOM-immunized animals rapidly developed marked IL-2, IFN-gamma (type 1-like), and IL-4 responses that peaked after the second immunization. To determine which type of immune responses correlated with protection from infection, all animals were challenged intravenously with 50 50% infective doses of a rhesus cell-propagated, in vivo-titrated stock of a chimeric simian immunodeficiency virus-HIVSF13 construct. Protection was observed in the two groups receiving the rgp120 subunit vaccines. Half of the animals in the ISCOM group were completely protected from infection. In other subunit vaccinees there was evidence by multiple assays that virus detected at 2 weeks postchallenge was effectively cleared. Early induction of potent type 1- as well as type 2-like T-helper responses induced the most-effective immunity. (+info)
A new strategy for treating nets. Part 1: formulation and dosage.
(5/2621)
The conventional dosages of pyrethroid insecticides on mosquito nets assume that nets will be retreated at 6-12 month intervals. However, dosage should be related to washing of nets; if nets are only washed once or twice a year, their dosage requirements will be different to those which are washed fortnightly. A 'low-dose, frequent-wash' retreatment system might be technically more appropriate and more affordable where nets are washed frequently, as they are in Dar es Salaam. Moreover, for use as a domestic insecticide, water-based formulations of pyrethroid are preferable to the more commonly used emulsifiable concentrates (ECs). This paper reports laboratory evaluations of three formulations (ECs, Flowable, CS) of three pyrethroids (deltamethrin, lambdacyhalothrin, permethrin). Insecticidal activity was tested using serial bioassays at a range of dosages using Anopheles gambiae. The water-based formulations were no less effective than the ECs, even at the lowest dosages. Nets treated with 3 mg/m2 and then repeatedly washed and retreated after each wash with either 3 mg/m2 or 1 mg/m2 were subjected to gas chromatography analysis. This showed that the amounts of pyrethroid in the nets accumulated rapidly over the first few wash-retreatment cycles and then remained fairly stable over subsequent cycles. These nets gave consistently high bioassay mortalities throughout the experiment, while the mortality declined rapidly after several washes with the nets that were treated at 3 mg/m2 but not retreated. Experimental huts were used to compare the effectiveness of these 2 net retreatment regimes and nets which were not retreated. All nets caused high mortality rates amongst Anopheles females, but had negligible effects on culicines; either in killing them or in preventing feeding. Therefore use of a high 'loading' dose for initial treatment with lower 'maintenance' doses for retreatment may be preferable to ensure that net users promptly perceive the benefits of the insecticide against culicines. (+info)
A double-blind, randomized, multicentre, crossover study to prove equivalence of pancreatin minimicrospheres versus microspheres in exocrine pancreatic insufficiency.
(6/2621)
BACKGROUND: Modern pancreatin preparations consist of enteric-coated microspheres to protect the enzymes from gastric acid. There are, however, no clinical trials comparing different sizes of pancreatin microspheres with regard to fat excretion and fat intake. AIM: To prove both equivalent efficacy and safety of conventional pancreatin microspheres and smaller pancreatin minimicrospheres in patients with exocrine insufficiency due to chronic pancreatitis. METHODS: In this prospective, randomized, double-blind, multicentre, crossover trial, patients with a stool fat excretion of > 7.5 g/day during a placebo period were randomly assigned either to the minimicrosphere/microsphere treatment sequence or vice versa. The primary end-point was the coefficient of fat absorption, which was calculated from fat excretion and fat intake during the course of a standardized diet. Stool weight, clinical symptoms and the safety of the preparations were also evaluated. RESULTS: Thirty-seven patients entered the study, of whom 23 fulfilled the criteria for the crossover period. In the per protocol analysis (n=18), the 90% confidence intervals for the coefficient of fat absorption of both crossover periods lay entirely within the equivalence range (P=0.02). The intention-to-treat analysis revealed similar results, but the equivalence range was slightly missed (P=0.07). Similar results were obtained for the secondary parameters and the reported adverse events. CONCLUSIONS: Pancreatin minimicrospheres have been shown to be equally effective as microspheres in improving the coefficient of fat absorption in patients with exocrine insufficiency due to chronic pancreatitis. (+info)
Pharmacokinetic and pharmacodynamic characterization of OROS and immediate-release amitriptyline.
(7/2621)
AIMS: To characterize the pharmacokinetics of amitriptyline and its metabolite nortriptyline following OROS and IR treatments, and to correlate them with anticholinergic side-effects. METHODS: The pharmacokinetics and safety of amitriptyline following administration of an osmotic controlled release tablet (OROS and an immediate release (IR) tablet were evaluated in 14 healthy subjects. In this randomized, open label, three-way crossover feasibility study, the subjects received a single 75 mg OROS tablet, three 25 mg IR tablets administered every 8 h, or 3x25 mg IR tablets administered at nighttime. In each treatment arm serial blood samples were collected for a period of 84 h after dosing. The plasma samples were analysed by gas chromatography for amitriptyline and its metabolite nortriptyline. Anticholinergic effects such as saliva output, visual acuity, and subject-rated drowsiness and dry mouth were measured on a continuous scale during each treatment period. RESULTS: Following dosing with OROS (amitriptyline hydrochloride), the mean maximal plasma amitriptyline concentration Cmax (15.3 ng ml-1 ) was lower and the mean tmax (25.7 h) was longer than that associated with the equivalent IR dose administered at nighttime (26.8 ng ml-1 and 6.3 h, respectively). The bioavailability of amitriptyline following OROS dosing was 95% relative to IR every 8 h dosing, and 89% relative to IR nighttime dosing. The metabolite-to-drug ratios after the three treatment periods were similar, suggesting no change in metabolism between treatments. The relationships between plasma amitriptyline concentration and anticholinergic effects (e.g. reduced saliva weight, dry mouth, and drowsiness) were similar with all three treatments. Of the anticholinergic effects, only decreased saliva weight and dry mouth correlated well with plasma amitriptyline concentrations; drowsiness did not. There was no apparent correlation between anticholinergic effects and the plasma nortriptyline concentration. CONCLUSIONS: The bioavailability of OROS (amitriptyline hydrochloride) was similar to that of the IR treatments and the pharmacokinetics of amitriptyline after OROS dosing may decrease the incidence of anticholinergic effects compared with that seen with nighttime dosing of the IR formulation. Therefore, this controlled-release formulation of amitriptyline may be appropriate for single daily administration. (+info)
The pharmacology of gene therapy.
(8/2621)
The objective for human gene therapy is to express exogenous DNA at a site in vivo for long enough, and at sufficient levels to produce a therapeutic response. The obstacles to this objective are numerous and include the formulation or packaging of the DNA, in vivo delivery, penetration of biological barriers, DNA elimination within the cell and from the tissue compartments of the whole body, control of product expression and overt toxicity. The current challenge is to resolve each of these obstacles to produce a practical and efficient gene therapy. In doing so, it is vital to understand the disposition of DNA vectors in vivo, and to know how conventional medicines may be used to modulate this disposition and to enhance the therapeutic effect of these vectors. Many of the general concepts of human gene therapy have been reviewed extensively in the literature. This review discusses some of the pharmacological aspects of gene delivery and the fate of vectors in vivo, and then highlights how drugs are being used to modulate gene therapy. (+info)