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At least 19 recordsLinked to original sources

Absolute concentrations of dithranol and triacetyl-dithranol in the skin layers after local treatment: in vivo investigations with four different types of pharmaceutical vehicles.

The pharmacokinetics of dithranol (anthralin) and its triacetate were investigated by employing a method which determines the quantity of the drug that penetrated into single layers of the human skin in vivo. For this purpose, tritium-labeled dithranol or triacetyl-dithranol was incorporated into four different ointments. The ointments were applied to the skin and biopsies were taken after 10, 30, 100, and 1000 min. The horny layer was removed before biopsy by Scotch tape stripping. The biopsies were sliced horizontally and the tritium determined in each sample. Dithranol as well as its triacetate penetrated best from more hydropholic ointments (Vaseline and aqueous wool-wax-alcohol ointment). From hydrophilic ointments (polyethylene glycol ointment and aqueous hydrophilic cream), only poor penetration was observed. Dithranol penetrated in far greater amounts than its triacetate, and the two compounds revealed fundamentally different penetration kinetics in epidermis and dermis. The data indicate that the triacetate was not split into its parent compound, dithranol, in substantial quantity, as the data obtained show the criteria of two independent substances.

Adult

Hemolysis of erythrocytes by primary pharmacologic agents, part 2: influence of the vehicle.

The hemolytic activity in vitro of chlorpromazine hydrochloride, chlordiazepoxide hydrochloride and brompheniramine maleate was examined using various intravenous solutions as the vehicle. Fresh human blood was employed in the investigation which used a colorimetric method for the determination of hemolysis. Prior to the examination of the hemolytic activity of each drug in the various vehicles, the vehicles themselves were examined for their ability to protect erythrocytes from hemolysis. Little to no hemolysis occurred in normal saline solution (the standard), dextrose 2.5% in normal saline, dextrose 5% in normal saline, dextrose 10% in normal saline, and lactated Ringer's injection. Low levels of hemolysis occurred in dextrose 5% in water, invert sugar 10% in water, and M/6 sodium lactate in water. High levels of hemolysis occurred when red blood cells were suspended in dextrose 2.5% in water. Invert sugar 10% in normal saline and fructose 10% in water caused red cell denaturation resulting in brown cells and hemolysate rather than the characteristic red color. This denaturation was attributed to the hydrogen ion concentration of these two solutions, both having pH values less than 4.0. Vehicles of dextrose in saline, dextrose in water, lactated Ringer's, and invert sugar in water reduced the level of drug-induced hemolysis for the drugs tested compared to that which occurred in normal saline solution. The reduction of hemolysis was greater as the tonicity of the vehicle used was increased. It was concluded that the pharmaceutical vehicles examined have an influence on the cellular effects of drugs which only affects the erythrocyte but which could potentially affect the drugs' distribution from the blood to the sites of their action.

Brompheniramine

Cosolvency of dimethyl isosorbide for steroid solubility.

Dimethyl isosorbide (DMI), which is currently under investigation for its potential use as a pharmaceutical vehicle and drug permeation enhancer, is a water-miscible liquid with relatively low viscosity. The solubilization behavior of DMI as a cosolvent for nonpolar drugs was characterized via dielectric constant measurements of binary solvent systems containing DMI and either water, propylene glycol (PG), or polyethylene glycol (PEG). Evidence from the dielectric constant profiles and NMR studies suggest that DMI undergoes complexation with water and PG, but not with PEG, through hydrogen bonding interactions. The solvent complexation exhibited a major effect on the solubilities of prednisone, dexamethasone, and prednisolone in the mixed solvent systems. Maximum solubility of each drug was found to occur near a DMI/water or DMI/PG concentration ratio of 1:2. In the DMI-PEG mixed system, while there is no apparent interaction between DMI and PEG molecules, the solubility of prednisone was found to increase with decreasing dielectric constant.

Dexamethasone

Investigation of some materials as dry binders for direct compression in tablet manufacture. Part 1: flow properties and water sorption.

Four substances were evaluated for their potential usefulness as dry binders for direct compression techniques in tablet making. The flow properties of these substances including angle of repose, timed delivery through an orifice and compressibility were determined. The effect of particle size of the binder on its flow properties was investigated. Comparative rates of water sorption demonstrated by the various substances evaluated as dry binders were also determined.

Absorption

Investigation of some materials as dry binders for direct compression in tablet manufacture. Part 2: Comparative self-binding properties.

Comparative self-binding qualities of four substances studied as potential dry binders for direct compression applications in tablet making were investigated. The effect of particle size of these materials on hardness, friability and hardness-friability ratio of disks made with mere binders was studied. The results showed that for comparable particle sizes, values of hardness-friability ratio of the various disks were in the following descending order: Plasdone, tragacanth, Carbowax 4000 and then mannitol.

Excipients

Vehicle effects on activity of an anticonvulsant compound.

The effect of several lipid and nonlipid pharmaceutical solvents on the in vivo activity of 1-diphenylmethyl-4- [(6 methyl-2-pyridyl) methyleneamino] piperazine (I) was evaluated in the mouse. The intensity of onset and the duration of anticonvulsant activity of the compound were affected depending on th type and form of liquid dosage preparation used. The rate of decline in anticonvulsant activity in the 80-20% response range followed apparent zero-order kinetics. A linear relationship between the observed ED50 and the concentration of sorbitol in the dosage form of I was observed. A reduction in the sorbitol content of the dosage form resulted in a proportional increase in the rapidity of onset and the duration of anticonvulsant activity of I. Emulsification restored both the onset and duration of pharmacological activity, which was virtually arrested when the compound was given orally as a solution in oil.

Animals

The evaluation of the force to expel oily injection vehicles from syringes.

Measurement of the force needed to expel oily injection vehicles from all-glass syringes through hypodermic needles has shown that the force required to maintain various rates of expulsion is in agreement with a modified form of the Poiseuille equation. The flow from disposable plastic syringes with rubber plunger tips fits this equation only if a correction is made to take account of the resistance to movement of the plunger (which is effectively zero for all-glass syringes). This resistance or binding force was shown to be increased by exposure to vegetable oils, and its magnitude was inversely dependent on vehicle viscosity. This increase was caused by swelling of the rubber plunger tips due to uptake of the oily vehicles by the rubber. No such increase in binding force was observed with a viscous aqueous vehicle.

Oils