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Biomedical subjects

M A Brooks

Publications and source records attributed to M A Brooks.

At least 37 records · Page 2Linked to original sources
PubMed1989

The determination of 4-amino-1-hydroxybutane-1,1-diphosphonic acid monosodium salt trihydrate in pharmaceutical dosage forms by high-performance liquid chromatography.

A rapid, sensitive and specific high-performance liquid chromatographic (HPLC) assay is reported for the determination of 4-amino-1-hydroxybutane-1, 1-diphosphonic acid (AHBuDP) monosodium salt trihydrate, a new inhibitor of bone resorption. The compound does not demonstrate any intrinsic UV properties and thus pre-column derivatization of the primary amino group of the drug with 9-fluorenylmethyl chloroformate (FMOC) at pH 9 in the presence of sodium citrate is required to facilitate UV detection of the analyte. Excess derivatization reagent is extracted with methylene chloride and an aliquot of the aqueous portion is assayed on a polymeric phase (Hamilton PRP-1) at 35 degrees C by reversed-phase HPLC. A mobile phase of 0.05 M citrate and 0.05 M phosphate buffer (pH 8.0)-acetonitrile-methanol (75:20:5, v/v/v) is utilized with UV detection at 266 nm. Application of the method to the analysis of AHBuDP in I.V. solution, tablet and capsule formulations is presented.

Alendronate↗
PubMed1988

A flow injection system with in-series ultraviolet and electrochemical detection for the simultaneous determination of lovastatin and butylated hydroxyanisole in a tablet.

A flow injection (FI) method has been developed to determine simultaneously a drug with an ultraviolet chromophore, lovastatin, and butylated hydroxyanisole (BHA) in a tablet. The system involves ultraviolet (UV) absorbance detection for the drug and oxidative amperometric electrochemical detection for BHA. The method has been shown to be reproducible for routine determinations with an accuracy of +/-1% for lovastatin and +/-4% for BHA. Precision for both analytes was approximately +/-1% (RSD). The use of FI compared with HPLC for these determinations has led to a dramatic decrease in the time required per assay. The method with UV detection has been shown to be specific for the drug in the presence of potential autoxidation products as well as BHA and its oxidation products. The use of electrochemical detection in series allows the method to be simultaneously specific for low levels of BHA (40 microg/tablet) in the presence of its oxidation products as well as the drug and its potential autoxidation products.

Journal Article↗
PubMed1986

High-performance liquid chromatography with ultraviolet or electrochemical detection for the determination of dopazinol in a pharmaceutical formulation.

The high-performance liquid chromatographic (HPLC) analysis of dopazinol, an anti-Parkinsonian drug, using either ultraviolet (UV) absorbance detection at 282 nm or oxidative amperometric electrochemical detection at the glassy carbon electrode (+0.92 V vs. Ag/AgCl) is described and evaluated. The influence of such factors as mobile phase composition, pH and column temperature on the detection of dopazinol using both detectors is reported. The HPLC analysis of samples resulting from the development and evaluation of a pharmaceutical formulation demonstrated a precision of less than 2.5% (R.S.D.) in the working ranges of the UV and electrochemical detectors. The limits of detection were 100 ng/ml for the UV detector and 1 ng/ml for the electrochemical detector. The higher sensitivity of the latter makes its use appropriate for the analysis of samples with low concentrations of dopazinol. Studies to compare the UV and electrochemical detectors for the routine analysis of dopazinol in pharmaceutical formulations are presented.

Antiparkinson Agents↗
PubMed1986

The economic cost of pelvic inflammatory disease.

Pelvic inflammatory disease (PID) is one of the most widespread and debilitating diseases affecting women today. To calculate the economic costs of PID and PID-associated ectopic pregnancy and infertility in the United States, we analyzed data from local hospitals and from several state and national sources. Direct and indirect costs were computed. We found that the total cost of PID and PID-associated ectopic pregnancy and infertility exceeded +2.6 billion in 1984. By 1990, the estimated cost of PID and its sequelae will total +3.50 billion per year, if the annual medical care inflation is 5% and the incidence of PID remains constant during this six-year period. These estimated costs of PID and its associated sequelae emphasize the urgent need for effective programs to prevent PID.

Absenteeism↗
PubMed1986

Determination of piquindone in canine plasma and urine by high-performance liquid chromatography.

This report describes a rapid, sensitive and selective method for the determination of piquindone in canine plasma and piquindone and the N-demethyl metabolite of piquindone in canine urine, utilizing normal-phase high-performance liquid chromatography (HPLC) with isocratic elution at ambient temperature and monitoring the ultraviolet absorbance of the eluent at 254 nm. The trimethyl analogue of piquindone is used as the internal standard in the HPLC assay of plasma. The assay was applied to the measurement of concentrations of piquindone in the plasma and urine of a dog following single intravenous and oral administration of 5 mg/kg doses of piquindone hydrochloride dihydrate.

Administration, Oral↗
PubMed1985

Determination of 4-amino-5-ethyl-3-thiophenecarboxylic acid methyl ester and its acid metabolite in plasma and urine by high-performance liquid chromatography.

Two separate, rapid, sensitive and selective high-performance liquid chromatographic (HPLC) assays were developed for the determination of 4-amino-5-ethyl-3-thiophene-carboxylic acid methyl ester (I) and its acid metabolite, 4-amino-5-ethyl-3-thiophene-carboxylic acid (II), in plasma and urine. The analysis of I is performed directly on a hexane extract of plasma or urine (buffered to pH 11) by normal-phase HPLC analysis using a 10-micron silica gel column with an eluting solvent of hexane-ethanol (95:5) and UV detection of the effluent at 254 nm. A methyl analogue, 4-amino-5-methyl-3-thiophenecarboxylic acid methyl ester, was used as the internal standard. The analysis of II is performed on the residue of either a diethyl-ether-washed protein-free filtrate of plasma or a methylene chloride-isopropanol (95:5) extract of urine (buffered to pH 5.3) using a 10-micron alkyl phenyl (reversed-phase) column with an eluting solvent of water-methanol-1 M phosphoric acid, pH 2.5 (70:30:0.05) with UV detection of the effluent at 254 nm. An isopropyl analogue, 4-amino-5-isopropylthiophene-3-carboxylic acid (IV), was used as the internal standard. The assay of compounds I and II were applied to the determination of plasma and urine concentrations of I and II in the dog and in man following oral administration of I X HCl. The data obtained demonstrated the extremely rapid and virtually complete deesterification of I (ester) to II (acid) in both species.

Animals↗
PubMed1985

Determination of chlorprothixene and its sulfoxide metabolite in plasma by high-performance liquid chromatography with ultraviolet and amperometric detection.

This communication describes a rapid, sensitive and selective method for the assay of chlorprothixene and its sulfoxide metabolite in human plasma, using reversed-phase high-performance liquid chromatography. Alkalinized plasma was extracted with heptane--isoamyl alcohol (99:1), after addition of thioridazine as the internal standard. The residue obtained after evaporation of this extract was chromatographed on a cyano column, using acetonitrile--0.02 M potassium dihydrogen phosphate pH 4.5 (60:40) as the mobile phase with ultraviolet (229 nm) detection. Quantitation was based on peak height ratios over the concentration range of 5.0-50.0 ng/ml for both compounds with 85% and 90% recovery for chlorprothixene and its sulfoxide metabolite, respectively, using a 1.0-ml plasma sample. The assay chromatographically resolves chlorprothixene and the sulfoxide metabolite from the N-desmethyl metabolite, which can only be semi-quantitated owing to low and variable recoveries. The method was used to obtain plasma concentration versus time profiles in two subjects after oral administration of 100 mg of chlorprothixene suspension and in two additional subjects following overdosages of chlorprothixene estimated to exceed several hundred milligrams. These analyses demonstrated that the sulfoxide metabolite is the predominant plasma component following therapeutic administration and overdosages. High-performance liquid chromatography with oxidative amperometric detection with the glassy carbon electrode was also evaluated. Although this procedure demonstrated comparable sensitivity and precision to ultraviolet detection for the analysis of chlorprothixene and N-desmethyl chlorprothixene, the sulfoxide metabolite could not be measured with high sensitivity (less than 100 ng/ml) owing to endogenous interferences. Hence the utility of this alternative assay technique is limited.

Adult↗
PubMed1983

Determination of cibenzoline in plasma and urine by high-performance liquid chromatography.

A rapid, sensitive and selective high-performance liquid chromatographic (HPLC) assay was developed for the determination of cibenzoline (CipralanTM) in human plasma and urine. The assay involves the extraction of the compound into benzene from plasma or urine buffered to pH 11 and HPLC analysis of the residue dissolved in acetonitrile-phosphate buffer (0.015 mol/l, pH 6.0) (80:20). A 10-microns ion-exchange (sulfonate) column was used with acetonitrile-phosphate buffer (0.015 mol/l, pH 6.0) (80:20) as the mobile phase. UV detection at 214 nm was used for quantitation with the di-p-methyl analogue of cibenzoline as the internal standard. The recovery of cibenzoline in the assay ranged from 60 to 70% and was validated in human plasma and urine in the concentration range of 10-1000 ng/ml and 50-5000 ng/ml, respectively. A normal-phase HPLC assay was developed for the determination of the imidazole metabolite of cibenzoline. The assays were applied to the determination of plasma and urine concentrations of cibenzoline and trace amounts of its imidazole metabolite following oral administration of cibenzoline succinate to two human subjects.

Chromatography, High Pressure Liquid↗
PubMed1983

Species specificity of immunity to malignant transformed cultured insect cells.

The specificity of malignantly transformed cultured cells of the German cockroach was assayed by injecting the cells into eight additional species of cockroaches in three families. All species but the most advanced one were susceptible. The range of lethal times for the different species reflected their relationship to the species from which the cells originated. The abilities of the injected hosts to encapsulate implants of embryo fragments of the German cockroach and microcarrier beads paralleled their resistance against the malignant cells. The order of susceptibility of the cockroach species to a pathogenic amoeba paralleled their susceptibility to the malignant cells, but death from the amoeba occurred in a much shorter time. Hematocrit values were higher in the more resistant species.

Amebiasis↗
PubMed1983

HLA in kinship determinations among Haitian immigrants.

Immunogenetic study of alleged first-degree relatives was undertaken among 258 prospective United States immigrants from Haiti. Methods involved serotyping red cells for ABO, Rh, and MN antigens and typing leukocytes for HLA, A, B, and C locus antigens. Kinship was definitely excluded in a relatively low 4.2% of cases involving putative parents and children. Among cases involving alleged siblings, estimates of fraud appeared slightly higher, but the method is suspect because even in true sibships, there may be an absence of obligatory gene markers. Data suggests that some cases involved half-siblings rather than fraud. Of demonstrated exclusions of parent or child, HLA detected the lack of kinship in 87.4% versus 16.9% by red cell typing. However, there were cases in which exclusions were found by red cell methods alone; furthermore, red cell plus HLA typing allows for a calculation of probability of kinship that is analogous to calculations in paternity studies. Together, the red cell and leukocyte systems offer a prior probability of exclusion of parent-child relationships in 91.3%.

Blood Grouping and Crossmatching↗
PubMed1982

Determination of the analgesic 3-phenoxy-N-methylmorphinan in plasma by gas chromatography using either positive chemical ionization mass spectrometric or nitrogen-phosphorus-specific detection analysis.

The compound 3-phenoxy-N-methylmorphinan (I) is under development as an analgesic agent. Studies on the biotransformation of the drug in the rat and in the dog have shown that I is extensively metabolized by N-demethylation to yield the nor-analogue (I-A), by para-hydroxylation of the 3-phenoxy ring to yield the phenolic analogue (I-B), cleavage of the ether linkage to yield levorphanol (I-C), and its N-demethylation to yield nor-levorphanol (I-D). The presence of these four metabolites (two of which, I-B and I-C, have analgesic potential) in addition to the parent drug, necessitated the development of sensitive and specific assays for their quantitation in plasma. This was accomplished by the development of (a) a high-performance liquid chromatographic assay using UV detection to obtain a qualitative/semi-quantitative profile of the metabolites present in plasma; (b) a gas chromatographic--nitrogen--phosphorus-specific detection method for the determination of the parent drug (I) for pre-clinical drug evaluation; and (c) a sensitive and specific gas chromatographic--positive chemical ionization mass spectrometric assay for eventual clinical evaluation for the determination of I and a key metabolite levorphanol (I-C). This report presents some preliminary pharmacokinetic data on I and I-C in the dog obtained during pre-clinical development.

Analgesics↗
PubMed1982

Determination of bromo-lasalocid in plasma by high-performance liquid chromatography with fluorimetric detection.

A rapid, sensitive, and specific high-performance liquid chromatographic (HPLC) assay was developed for the determination of bromo-lasalocid in plasma. The compound was extracted into isooctane-ethyl acetate (90:10) from plasma saturated with potassium chloride and adjusted to strongly alkaline pH. The residue of this extract was dissolved in methanol-2-methoxyethanol (95:5) and analyzed by HPLC on a 10-micrometer C18 column [mobile phase of methanol-water-2-methoxyethanol-1 M potassium phosphate buffer, pH 3.0 (90:10:2.5:0.2)] using fluorescence detection with excitation at 215 nm and emission at wavelengths greater than 370 nm. The overall recovery of the assay was 65%, with a limit of sensitivity of 0.1 microgram/ml. The method was used to obtain plasma concentration-time profiles in the dog following oral administration of bromo-lasalocid-ethanolate.

Animals↗
PubMed1982

Determination of amdinocillin in plasma and urine by high-performance liquid chromatography.

A rapid, sensitive and specific high-performance liquid chromatographic (HPLC) assay was developed for the determination of amdinocillin (formerly mecillinam) in human plasma and urine. The assay is performed by direct injection of a plasma protein-free supernatant or a dilution of urine. A 10 micrometer muBondapak phenyl column with an eluting solvent of water--methanol--1 M phosphate buffer, pH 7 (70:30:0.5) was used, with UV detection of the effluent at 220 nm. Azidocillin potassium salt [potassium-6-(D-(-)-alpha-azidophenyacetamido)-penicillanate] was used as the internal standard and quantitation was based on peak height ratio of amdinocillin to that of the internal standard. The assay has a recovery of 74.4 +/- 6.3% (S.D.) in the concentration ranges of 0.1-20 microgram per 0.2 ml of plasma with a limit of detection equivalent to 0.5 microgram/ml plasma. The urine assay was validated over a concentration range of 0.025-5 mg/ml of urine, and has a limit of detection of 0.025 mg/ml (25 microgram/ml) using a 0.1-ml urine specimen per assay. The assay was applied to the determination of plasma and urine concentrations of amdinocillin following intravenous administration of a 10 mg/kg dose of amdinocillin to two human subjects. The HPLC and microbiological assays were shown to correlate well for these samples.

Amdinocillin↗