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Biomedical subjects

R B Patel

Publications and source records attributed to R B Patel.

At least 37 records · Page 2Linked to original sources
PubMed1987

Preparation and evaluation of 99mTc(V)-DMSA complex: studies in medullary carcinoma of thyroid.

Consequent to the promising results reported with 99mTc(V)-DMSA for imaging certain types of soft tissue tumors, we have developed methods to prepare this radiopharmaceutical in three ways: from freshly prepared reagents, through the use of a two component kit and use of the standard renal DMSA kit by a modified recipe. The 99mTc(V)-DMSA complex has been subjected to paper electrophoretic and chromatographic procedures and also biodistribution studies. The distinctly different behaviour of this new product compared to that of the well known renal DMSA complex has been clearly established. Scintiimaging in a preliminary clinical trial in patients with medullary carcinoma of the thyroid has been encouraging.

Carcinoma↗
PubMed1987

Influence of tablet dissolution on furosemide bioavailability: a bioequivalence study.

In order to evaluate the in vitro dissolution and in vivo bioavailability relationship for furosemide, a bioequivalence study was carried out. Furosemide (40 mg) was administered orally to 12 normal volunteers in a 6 x 6 crossover design using six products (five tablets and one solution) obtained from three pharmaceutical companies. Plasma and urine concentrations of furosemide were quantitated by high-performance liquid chromatography (HPLC). Plasma furosemide profiles were analyzed by non-compartmental methods. Compared to the oral solution, all of the formulations exhibited lower peak furosemide concentrations, longer mean residence times, and, in some cases, diminished bioavailability (range, 66-96%). Similar results were obtained when the reference product (a rapidly dissolving tablet) was used as the standard. All of the products failed the 75/75 rule when compared to either reference standard, apparently because of large intersubject variability. The total amount of furosemide excreted in urine could be associated with the percentage drug dissolved (in vitro) at 30 min. The pH 5.6 dissolution medium (compared to pH 4.6) appears to be an appropriate test medium for assuring batch uniformity and bioequivalence of furosemide products.

Administration, Oral↗
PubMed1987

Calcium antagonists and blood glucose in normal rabbits.

The effects of the calcium antagonists verapamil and nifedipine on blood glucose levels, glucose tolerance, insulin secretion during glucose tolerance and hypoglycaemic effect of tolbutamide were studied in normal nondiabetic rabbits. Daily dosage of 40 mg/kg verapamil and 5 mg/kg nifedipine given orally up to 7 days did not affect blood glucose level, glucose tolerance, insulin secretion during glucose tolerance and hypoglycaemic activity of tolbutamide 250 mg/kg p.o.

Animals↗
PubMed1986

Acardiac anomaly: review of the subject with case report and emphasis on practical sonography.

The acardiac anomaly is a rare condition found only in monozygotic multiple pregnancies, usually twins. We present a review of the pathophysiology of acardia and a case report. Twin embryonic membrane formation is discussed, since a conceptual understanding of the subject is necessary for the early recognition of this and other severe anomalies. Emphasis is placed on close sonographic monitoring to insure the best chance of survival of the normal twin, who may die of heart failure if delivery is not properly timed.

Abnormalities, Multiple↗
PubMed1984

Bioavailability of hydrochlorothiazide from tablets and suspensions.

The bioavailability of hydrochlorothiazide was determined following single oral 25-, 50-, 100-, and 200-mg tablet and suspension doses in 12 healthy male volunteers. Plasma and urine levels of hydrochlorothiazide were determined by HPLC. Plasma levels of hydrochlorothiazide were satisfactorily described by a triexponential function. Mean peak plasma levels, Cmax (127-135, 270-280, and 437-490 ng/mL from the 25-, 50-, and 100-mg doses, respectively) were dose proportional, as were areas under plasma profiles, AUC0----36. Mean percentage recovery of unchanged hydrochlorothiazide in 48-h urine samples accounted for 50-59, 54-55, 60-63, and 54-57% of the 25-, 50-, 100-, and 200-mg doses, respectively. There were no significant differences among these values. Correlation coefficients between 48-h urinary recovery of hydrochlorothiazide and the plasma values (Cmax and AUC0----36) for the 25-, 50-, and 100-mg doses were 0.73 and 0.84. There were no differences in the net increases in electrolyte excretion among the treatments during the 0-12-h postdose period. The systematic availability of hydrochlorothiazide, unlike that of chlorothiazide, is dose proportional in the therapeutic range.

Adult↗
PubMed1984

Bioavailability of hydrocortisone from commercial 20-mg tablets.

The relative bioavailability of hydrocortisone was determined from four different 20-mg tablet formulations and one suspension in 15 healthy male volunteers; results were compared with in vitro dissolution rates. Plasma levels of hydrocortisone were determined by a liquid chromatography method developed in this laboratory. Dissolution of the tablet formulations, using the official USP test, varied from 7.8 to 93.8% in 30 min. Similar plasma profiles were obtained from all tablet products, and there were no differences among tablets in the cumulative percentage of drug absorbed. There were no clear trends in any pharmacokinetic parameter values among the tablet dosages, and the four products were considered bioequivalent. The suspension dosage yielded significantly higher plasma levels compared with some of the tablet formulations during the initial 30-min postdose, significantly higher cumulative absorption at 0.5 and 1.0 h compared with one tablet formulation, and significantly higher ka and Cmax, and shorter tmax values, compared with some of the tablets.

Adult↗
PubMed1983

Computed tomography demonstration of distal femoral (trochlear) articular groove: a normal variant.

In computed tomography of the skeleton, as in other radiologic modalities, recognition of normal skeletal variants is essential for defining the extent and type of injury or neoplasm. Computed tomography findings, because of the unique use of cross-sectional anatomy, must be carefully studied to avoid labeling a normal variant as an abnormal entity. We describe here an observation of a normal variant--distal femoral, anterior articular (trochlear) groove--found in a patient with an osteochondral fracture and loose intra-articular bony fragment.

Adult↗
PubMed1983

Reduction in oral penicillamine absorption by food, antacid, and ferrous sulfate.

Plasma levels of penicillamine, urinary recovery of penicillamine and its oxidized metabolites, and urinary excretion of copper were examined after single 500-mg oral doses of penicillamine to six healthy men. Penicillamine was given after an overnight fast, a standard breakfast, and after antacid and ferrous sulfate. Following the fasting dose, the mean peak plasma level of 3.05 micrograms/ml developed at 3.8 hr and the drug was cleared from plasma with a t1/2 of 2.1 hr. Penicillamine levels were reduced to 52%, 35%, and 66% of those from the fasting dose after food, ferrous sulfate, and antacid. The rates of penicillamine appearance and disappearance from plasma were essentially treatment independent. There were good correlations between urinary recovery of total penicillamine (r = 0.875), between urinary copper excretion (r = 0.758) and the penicillamine plasma concentration AUCs. The availability of oral penicillamine is very susceptible to interactions with other substances. Further studies may be necessary to assess the full clinical significance of these interactions.

Absorption↗