Showing papers by "Takeru Higuchi published in 1956"

The Physics of Tablet Compression IX: Fundamental Aspects of Tablet Lubrication

Abstract: A study of lubricants during compression and in finished tablets has shown that, (1) lubricants are confined to the surface and intergranular regions of the finished tablets and do not mix intimately with the contents of the granules, (2) approximately 1 per cent lubricant appeared to give nearly o timum granulation lubricity when applied to the test granulations used in this stucfy, (3) fluid lubricants appeared to flow into tablet voids and unlike solid lubricants did not usually cause significant increase in punch forces when added in increasing amounts if the machine settings and weights of die fill were constant, (4) the addition of lubricants, e. g., ma nesium stearate, to granulations tended to roduce slightly softer tablets and at t8e same time significantly prolonged tablet $isintegration time in the usual concentrations.

Possible Complex Formation BetweenMacromolecules and Certain Pharmaceuticals X* The Interaction of Some Phenolic Compounds with Polyethylene Glycols, Polypropylene Glycols, and Polyvinylpyrrolidone

Abstract: A photometric-titrimetric method and a dialytic method have been employed to obtain information as to the occurrence of complexes in several systems. Interactions of phenol with members of the polyethylene glycol series, with members of the polypropylene glycol series, and with polyvinylpyrrolidone have been studied. The influence on the complexing tendency of reactant concentration, of salt concentration in the system, of alcohol concentration in the system, and of temperature, has been investigated. The results show that the several systems behave essentially in the same manner despite the differences in the structures of the polymeric substances.

The Physics of Tablet Compression XI.:Determination of Porosity of Tablet Granulations

Abstract: A method is presented for determining the porosity of tablet granulations in which two different density measurements are employed. They are (a) the “true” or maximum density of the granules obtained by high pressure compression of samples of the granulations, and (b) the apparent density, determined by mercury displacement. The values resulting from these two measurements on a given granulation were used to calculate the per cent void space in the granules. This report includes data from applying the experimental procedures to four test granulations, potassium bromide crystals (10-20 mesh), and glass beads. The results indicate that granulations prepared by the wet granulation method, using starch paste, had approximately 30% void space, while aspirin granulation, prepared by the slugging process, had approximately 3% void space.

Inhibition of hydrolysis of esters in solution by formation of complexes. II. Stabilization of procaine with caffeine

Abstract: A study of the tetracaine hydrochloride-caffeine system has shown that the hydro-lytic rate of the ester component is reduced in the presence of the xanthine in a manner similar to that of the benzocaine-caffeine and the procaine hydrochloride-caffeine systems. Evidence seems to indicate however, that the stoichiometry of the complexing reaction is different from the previous cases. The data obtained are best rationalized on the basis that tetracaine ion forms two types of complexes in solution, the first consisting of two caffeine molecules to one tetracaine ion and the second of two tetracaine ions to one caffeine molecule. According to the present findings, addition of one-half per cent caffeine to a similar concentration of tetracaine hydro-chloride in water, for example, reduces the hydrolytic rate by thirty-five per cent. In the presence of two per cent caffeine, the rate of hydrolysis is only one-third that of the caffeine-free solution.

Interaction Studies of Cationic Drugs with Anionic Polyelectrolytes I: Sodium Carboxymethylcellulose

Abstract: A study of the interaction of sodium carboxymethylcellulose with a number of cationic drugs indicated that even prior to the formation of visible reaction products, binding of the drug ions on the dissolved polyelectrolyte occurs. It has been shown that CMC forms complexes in this manner with the cationic drugs quinine, Benadryl®, procaine, and Pyribenzamine®. With amphetamine and ephedrine only the Donnan effect appears to be operative. Sodium chloride will to a great extent displace the bound cations from the CMC. A method utilizing a dialysis technique and Donnan equilibrium concepts has been presented.

Formation of molecular complexes by some water‐soluble amides I. Interaction of several amides with p‐hydroxybenzoic acid, salicylic acid, chloramphenicol, and phenol

Abstract: On the basis of previously proposed theories, molecules possessing amide groupings would be expected to exhibit ability to form molecular complexes similar to caffeine complexes with certain proton donors. Data are presented to show that amides formed between dimethylamine and several dibasic acids have this property. Both soluble and insoluble complexes seem to result when these agents are added to hydroxybenzoic acids, chloramphenicol, and phenol.

Formation of molecular complexes by some water-soluble amides. II. Effect of decreasing water solubility on degree of complex formation.

Abstract: The formation of molecular complexes in aqueous solution was generally enhanced, as expected, by the “squeezing out” effect of water on complexing agents rendered less water‐soluble by structural modifications. The stereochemical effect, however, appears to impose limitations on these modifications. Substitution of ethyl for methyl in several dialkyl amides resulted, in most cases, in an apparent increase in complex formation and marked decrease in the solubility of the complex formed.

Physical chemical properties and ultraviolet spectral characteristics of amyl nitrite

Abstract: The ultraviolet spectra of amyl nitrite, which has been determined in various polar and nonpolar solvents, exhibits rather unusual details in the long ultraviolet range. Attempts have been made to ascertain whether this behavior can be directly attributed to pure amyl nitrite or whether it is due to a persistent impurity. The apparent molar absorbance of the drug is unexpectedly low. The vapor pressure of amyl nitrite has been determined as a function of temperature by the Ramsey‐Young method.