Biomedical subjects

L Vlase

Publications and source records attributed to L Vlase.

14 recordsLinked to original sources

PubMed2004

Fast determination of colchicine by TLC-densitometry from pharmaceuticals and vegetal extracts.

Colchicine, (S)-N-(5,6,7,9-tetrahydro-1,2,3,10-tetramethoxy-9-oxobenzo-(a(-heptalen-7-yl)-acetamide, is the main alkaloid contained in Colchicum autumnale (meadow saffron). There are known colorimetric, spectrophotometric, volumetric, potentiometric, voltametric, gravimetric and various chromatographic methods for quantitative determination of colchicine, each of them presenting a series of advantages and disadvantages. As an alternative, we proposed the use of a densitometric determination for colchicine allowing the determination of this alkaloid from pharmaceutical products, as well from seeds of meadow saffron. The total alkaloid extract was separated by Thin-Layer Chromatography using Silicagel 60F(254) layers and a mixture of chloroform:acetone:diethylamine (5:4:1) as mobile phase. The same conditions were used for the determination from pharmaceutical products. Densitometric measurements were carried out at the absorption maximum (350 nm) of colchicine, the determinations being made by reflectance and by fluorescence. The peaks were optimized regarding to their area and shape by varying four scanning parameters (slit width and height, number of measurements and scanning speed). We established the calibration plot using pure colchicine in the range 50-600 ng mL(-1). The proposed method could be widely used in the pharmaceutical industry for the quick and accurate quantitative determination of colchicine because it eliminates the interferences given by other bioactive or degradation compounds. The method was characterized by validation parameters (linearity, accuracy, fidelity, sensitivity) and it was established its performances in comparison with an HPLC method and an official quantitative determination from the Romanian Pharmacopoeia X edition respectively.

Chromatography, Thin Layer↗

PubMed2004

A pharmacokinetic interaction study between omeprazole and the H2-receptor antagonist ranitidine.

The effect of ranitidine pretreatment on the pharmacokinetics of omeprazole was investigated in 14 male human volunteers. Omeprazole (40 mg, gastroresistant pellets) was administered to the volunteers in a two-treatment study design, either alone or after 5 days pretreatment with b.i.d. doses of 150 mg ranitidine. Plasma concentrations of omeprazole were determined over a 24-hour period following drug administration, by a validated RP-HPLC method. Pharmacokinetic parameters were calculated with compartmental and non-compartmental analysis, using the computer program Kinetica (Inna Phase). In the two periods of treatments, the mean peak plasma concentrations Cmax were 730.8 ng/ml for omeprazole alone and 802.1 ng/ml for omeprazole co-administered with ranitidine (not significant). The time taken to reach the peak, Tmax, was 1.29 h and 1.42 h, respectively (not significant). The areas under the curve (AUC0-10) were 1,453.3 ng.h/ml and 1,736.8 ng.h/ml for the two periods of treatment; thus a greater AUC was obtained after pretreatment with multiple doses of ranitidine. Our data show that the pharmacokinetics of omeprazole might be inhibited by pretreatment with ranitidine; however, the clinical relevance of this interaction still has to be confirmed.

Adult↗

PubMed1992

Congenital adrenal hyperplasia with female pseudohermaphroditism in a 26-year-old patient.

The paper presents the case of a 26-yr-old patient admitted for intersexuality. Clinical examination shows statural deficit, female phenotype, melanoderma, glabrous tegmina except for the pubic area presenting horizontally inserted pilosity, labioscrotum devoid of contents, pseudomicropenis with hypospadias. The Barr cytogenetic test is positive (56%) and hormone assay shows plasma cortisol at the lower limit and adrenal androgenic hormones and their metabolites in excess, suppressible by dexamethasone. The patient had a history of repeated admissions to intensive care units for severe dehydration, vomiting, diarrhea and collapse.

Adrenal Hyperplasia, Congenital↗

PubMed1991

Cardiac disturbances in thyrotoxicosis: diagnosis, incidence, clinical features and management.

In the present paper we studied 403 patients with different etiopathogenic and clinical forms of thyrotoxicosis: toxic multinodular goiter (36.7%), toxic adenoma (4.9%), Graves' disease (27.04%), transient thyrotoxicosis (subacute thyroiditis, painless thyroiditis, Hashitoxicosis) (21.09%), T3-thyrotoxicosis (9.42%), thyrotoxicosis factitia (0.74%). Eighty-seven patients (21.5%) had cardiac disturbances. The following arrhythmias were most common: atrial fibrillation (4.00%), ventricular premature beats (2.77%), paroxysmal supraventricular tachycardia (2.23%), atrial flutter (1.00%). Congestive heart failure occurred in 10.42% of the cases. Paroxysmal tachyarrhythmias were converted to sinus rhythm in 90% of the subjects, by a selected and sustained treatment: drug therapy (carbimazole 30-40 mg/day, Lugol solution 1/2/20, 10-15 drops/day, beta-adrenergic blockers (propranolol--60-120 mg/24 hrs), calcium channel blockers (verapamil--40-60 mg/24 hrs), cardiac glycosides (deslanosid) or DC cardioversion. In order to prevent recurrences and/or complications, drug therapy was subsequently completed with subtotal thyroidectomy or radioactive iodine (131I) therapy. Thus, we succeeded in maintaining the patients in a euthyroid state, in sinus rhythm and with an adequate cardiovascular function in 95.4% of the cases.

Adult↗

PubMed1973