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Biomedical subjects

L T Grady

Publications and source records attributed to L T Grady.

At least 19 recordsLinked to original sources
PubMed1982

Purity profiles of pteroylglutamate reference substances by high-performance liquid chromatography.

High-performance liquid chromatography (HPLC) in the reversed-phase mode was used for the purity analysis of three pteroylglutamic acid-type reference substances (folic acid, leucovorin calcium, and methotrexate). The influence of the pH of the mobile phase on the separation of an artificial mixture of six pteroylglutamic acid derivatives and three potential impurities was studied. Results of purity analysis of current lots of USP reference standards are reported. A better separation of methotrexate from its major impurities was achieved by using a standard buffer, rather than an ion-pairing mobile phase. A separation of methotrexate and its biologically inactive 7-isomer is reported.

Chromatography, High Pressure Liquid↗
PubMed1981

Effects of packaging and storage on the dissolution of model prednisone tablets.

The effects of packaging and storage in multiple-unit and unit-dose containers on dissolution rate of model prednisone tablets are reported. USP Prednisone Dissolution Calibrator Tablets were packaged in three multiple-unit and five unit-dose containers. Packaged tablets were stored for three to six months under three conditions: 40 degrees C and 85% relative humidity (R.H.), 37 degrees C and 75% R.H., and 22 degrees C and 75% R.H. Dissolution rate was measured at pre-determined intervals during storage. For each condition tested, two separate runs of six tablets each were performed. Tablets in the least moisture-permeable containers were least affected by storage. The conditions of high heat and humidity caused the greatest change in dissolution rate. When stored at 22 degrees C and 75% R.H., little change in dissolution rate occurred in any packaged tablets. It is concluded that packaging and storage conditions affect tablet dissolution characteristics markedly. The practice of labeling repackaged tablets with the expiration date of the original container is shown to be invalid.

Adsorption↗
PubMed1980

Stability of solid drugs: degradation of ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3) at high humidities and elevated temperatures.

Ergocalciferol and cholecalciferol powders were studied at 25 and 40 degrees and at different humidities. Ergocalciferol decomposed rapidly at 25 and 40 degrees when stored in dry air. Decomposition of ergocalciferol led to the formation of products of higher polarity. Cholecalciferol was not as labile under dry conditions, but decomposed rapidly at high temperature.

Cholecalciferol↗
PubMed1978

Gas-liquid chromatographic determination of p-chloroacetanilide in acetaminophen.

Gas-liquid chromatography GLC) coupled with column chromatography was used to accurately determine as little as 25 ppm p-chloroacetanilide in acetaminophen. p-Chloroacetanilide was eluted from a pH 8 phosphate-buffered diatomite partition column by using purified tetrachloroethylene (acetaminophen was retained). This solution was concentrated, internal standard (docosane) was added, and p-chloroacetanilide was determined by using a 0.9 m X 2 mm glass column packed with 3% Poly A 103 on Supelcoport and a flame ionization detector with electronic integration. Standard curves were linear for 10-100 ppm p-chloroacetanilide. Various chromatographic materials were investigated for optimal retention characteristics. High pressure liquid chromatography (HPLC) was also evaluated as an alternative; however, lack of reproducibility of the HPLC column favored the GLC procedure.

Acetaminophen↗
PubMed1978

Moisture permeation of newer unit dose repackaging materials.

Moisture permeation of some unit dose repackaging materials currently available was tested and compared with the results of an earlier study. Seventeen unit dose containers marketed for hospital pharmacy repackaging were tested. Most of the samples were prepared in a laboratory under optimal physical and mechanical conditions. The methodology involved packaging a desiccant pellet, storage at 75 +/- 3% relative humidity and 20 +/- 2 C, and weighing at various time intervals. Each container was placed into one of four classes depending upon the amount of weight gain. In general, moisture permeation values for all types of materials were much lower than in the previous study. The results show that improved moisture protection can be achieved through modifications in typical repackaging systems.

Drug Packaging↗
PubMed1977

Chromatographic assays for folic acid.

TLC and high-pressure liquid chromatographic (HPLC) assays for folic acid were developed. In the TLC procedure, the folic acid band was extracted from the silica gel after development and determined spectrophotometrically by an oxidation and Bratton-Marshall sequence. A column packed with octadecylsilane chemically bonded to microparticulate silica gel was used for the HPLC assay. Potentiometric determination of water in folic acid samples was necessary to obtain accurate purity values. In a comparison of four assay methods, a direct colorimetric method gave precise, but unspecific, results, while the USP XIX colorimetric method lacked both precision and specificity. The two chromatographic methods were both precise and specific and gave the same assay results. Both methods separated p-aminobenzoic acid, N-(p-amino-benzoyl)-L-glutamic acid, 2-amino-1,4-dihydro-4-oxo-6-pteridinecarboxylic acid, 2-amino-4(1H)-pteridinone, and several unidentified impurities from folic acid.

Chromatography, High Pressure Liquid↗
PubMed1977

Moisture permeation of typical unit does repackaging materials.

The moisture permeation of unit does repackaging materials used by various hospital and community pharmacies in a metropolitan area was studied. Commercial desiccant pellets were packaged in the same manner used for ordinary tablets and capsules. The samples were weighed and placed in a controlled chamber at about 75% relative humidity and 22 C, and tested for weight gain over a period of 4-10 days. Four types of packages were evaluated: (1) heat-sealed polyethylene bag, (2) polyvinyl chloride cups adhesive-sealed to multiple-ply paper, (3) heat-sealed "polycel-polyfoil" strip packages and (4) polyvinyl chloride/foil multiple-cup blister packs. A wide range of results was found. None of the containers tested was a good moisture barrier, although some offered protection for a limited time. Several needs were identified by this survey. Pharmacists need more information and an increased awareness concerning the permeation characteristics of repackaging materials, suitable operating procedures and the stability of pharmaceutical products. Standards must be established for repackaging materials as well as limits on storage periods for the repackaged pharmaceuticals. Procedures for pharmacists to test their own packaging systems, and a checklist of some important guidelines for repackaging in unit dose containers, are presented.

Drug Packaging↗
PubMed1976

GLC assay of belladonna extracts.

Samples of belladonna pilular and powdered extract and tincture from two suppliers were analyzed by GLC as a cooperative effort between two laboratories to develop methodology with substantial improvements in sensitivity, specificity, precision, and working time over the present official method. This goal was achieved, but marked differences in response of the individual extracts to different isolation schemes were noted.

Atropine↗