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Biomedical subjects

A Marzo

Publications and source records attributed to A Marzo.

At least 73 records · Page 4Linked to original sources
PubMed1991

Homeostatic equilibrium of L-carnitine family before and after i.v. administration of propionyl-L-carnitine in humans, dogs and rats.

Propionyl-L-carnitine is a minor component of L-carnitine family which, when exogenously administered, proved to possess interesting cardiovascular activities. In this paper the pharmacokinetics of propionyl-L-carnitine was investigated in humans, dogs and rats after intravenous administration. In all the three species the base homeostatic equilibrium was carefully investigated in plasma and in urine during the 24 h period before the administration. Propionyl-L-carnitine, acetyl-L-carnitine, L-carnitine and total acid soluble L-sensitive were assayed in plasma and urine with very sensitive enantioselective radioenzyme assay. After dosing propionyl-L-carnitine rapidly increased, and then decreased reaching the base value within 6 h or more, depending on the species and the dose. Also L-carnitine in all the three species and acetyl-L-carnitine in rats and dogs increased, but the increase was more sustained when compared to propionyl-L-carnitine. Urinary excretion paralleled plasma concentration, reaching the highest value in the 24 h-period after dosing. Renal clearance also increased reflecting the behaviour of plasma concentration and urinary excretion. Results obtained all the conclusion that two homeostatic equilibrium of L-carnitine family components, namely the inter-exchange between L-carnitine and its esters catalyzed by carnitine acyl transferases, and a saturable tubular reabsorption process with differentiated threshold for each component.

Acetylcarnitine↗
PubMed1991

Protein binding of L-carnitine family components.

L-carnitine and its short-, medium- and long-chain acyl esters constitute the L-carnitine family. These compounds in the body are equilibrated according to a homeostatic equilibrium preserved and, when impaired, restored by a dynamic inter-exchange between L-carnitine and its esters, catalysed by carnitine acyl transferases, and a tubular reabsorption process with differentiated thresholds for each component. The interaction of these compounds with albumin and plasma proteins of rats, dogs and humans was carefully investigated by means of ultrafiltration and gel filtration techniques. Results obtained demonstrate that L-carnitine and its short-chain esters, namely acetyl-L-carnitine and propionyl-L-carnitine, do not interact with either albumin or plasma proteins; octanoyl-L-carnitine interacts in a measurable even if poor extent (12-30%), whereas palmitoyl-L-carnitine, a molecule with a detergent activity, is completely bound to albumin and plasma proteins.

Acetylcarnitine↗
PubMed1990

Assay of hydroxyfarrerol in biological fluids.

A high-performance liquid chromatographic method for the determination of hydroxyfarrerol (IdB 1031) in biological samples was developed. IdB 1031 was first extracted by liquid-solid partition and the extracts were evaporated and analysed on a reversed-phase column under isocratic conditions, using either an electrochemical or a UV detector. The detection limit was ca. 5 ng/ml. Preliminary pharmacokinetic data showed that rats treated orally with 500 mg/kg had an average peak plasma concentration (Cmax) of 497 ng/ml after 2 h.

Administration, Oral↗
PubMed1990

Chromatographic and non-chromatographic assay of L-carnitine family components.

L-Carnitine and its acyl esters constitute an endogenous pool of the L-carnitine family, involved in the uptake of free fatty acids in the mitochondria by transfer across their membrane of the acyl moieties to fuel the beta-oxidation and the release of the acetyl group from the mitochondria to the cytosol. Therefore acyl-L-carnitine and acyl-L-carnitine transferase are involved in a homeostatic equilibrium with the cells. As most of these substances need to be monitored in foods, chemical and pharmaceutical processes and biological fluids, an overview of the main methods for assaying them is provided here, with specific reference to the intrinsic performance of each analytical procedure and with suggestions on the correct storage and manipulation of analytical samples.

Animals↗
PubMed1990

Pharmacokinetics of oral acetyl-L-carnitine in renal impairment.

Acetyl-L-carnitine 1.5 g and 3.0 g was administered as three divided doses on each of two occasions to 24 people with varying renal failure (creatinine clearance 127-8 ml.min-1). Plasma and urinary concentrations of total-L-carnitine, free (non-esterified) carnitine, short-chain esters and acetyl-L-carnitine were measured. The baseline (pre-study) concentrations of all four substances were related to renal function. Patients whose creatinine clearance was below about 30-40 ml.min-1 were had the highest concentrations. Renal elimination of all four substances was related to dose and to renal function. There was evidence for dose-related elimination, with greater elimination of the larger dose.

Acetylcarnitine↗
PubMed1990

High-pressure liquid chromatographic evaluation of cyclic paracetamol-acetylsalicylate and its active metabolites with results of a comparative pharmacokinetic investigation in the rat.

Like benorilate, its correlated open ester, MR 897, a cyclic ester between acetylsalicylic acid and paracetamol, gives rise to acetylsalicylic acid, salicylic acid and paracetamol by enzymatic hydrolysis. An analytical method was developed, which detects parent drugs and active metabolites, in order to compare the pharmacokinetic and metabolic behaviour of the two products. The method was specifically validated for quantitative analysis of salicylic acid and paracetamol, which are the main systemic metabolites of both MR 897 and benorilate. Extraction from plasma or tissue homogenate was carried out in two steps with diethyl ether and acetate. Recovery of the analytical substances ranged from 82.7% for paracetamol to 98.5% for salicylic acid. The results of a comparative pharmacokinetic investigation of MR 897 and benorilate in the rat confirm higher bioavailability and a more favourable plasma level profile with MR 897.

Acetaminophen↗
PubMed1990

Evaluation of ibuprofen dimethyl aminoethanol octyl bromide and related active metabolites in biological samples.

AF 150 is ibuprofen dimethyl aminoethanol octyl bromide, endowed with antibacterial and antiinflammatory activities. An indirect HPLC analytical method for AF 150 with UV detection, to be used for pharmacokinetic studies, has been validated in terms of linearity, reproducibility, specificity and sensitivity. Using this method the bioavailability of AF 150 and its active metabolite ibuprofen was investigated following parenteral administration and topical application.

Animals↗
PubMed1989

Metabolism and disposition of intravenously administered acetyl-L-carnitine in healthy volunteers.

The pharmacokinetics of acetyl-L-carnitine hydrochloride were investigated in 6 healthy volunteers of both sexes after i.v. injection of 500 mg of the drug, expressed as inner salt. Plasma concentrations and urinary excretion of acetyl-L-carnitine (A), L-carnitine (B) and total acid soluble L-carnitine fraction were evaluated over a period lasting from 24 h before to 48 h after the administration. Plasma concentrations of A increased quickly after administration and then declined reaching base values within 12 h. Conversely, plasma concentrations of B rose more slowly, reaching a peak in 30-60 min, and then declined to base values within 24 h. Most of the injected dose of acetyl-L-carnitine was recovered in the urine during the first 24 h after administration as B and A. Mean renal clearance of both A and B during the first 12 h after injection was higher than the base values, suggesting the presence of a saturable tubular reabsorption process which may counterbalance major changes occurring in plasma concentrations of L-carnitine pattern.

Acetylcarnitine↗
PubMed1989

Chromatographic methods and selective detectors in pharmacokinetics.

The quantitative evaluation of drugs in biological samples requires them to be estimated at concentrations associated with pharmacological activity, which range between fractions of ng and hundreds of ug per ml of plasma. Chromatographic techniques are generally used in this evaluation. This review deals with the detectors most frequently used in chromatographic apparatus (GLC and HPLC), their selective performance and the derivatization reactions involved in the quantitative evaluation of drugs in biological samples at active therapeutic concentrations.

Chromatography↗
PubMed1988

Application of high-performance liquid chromatography to the analysis of propionyl-L-carnitine by a stereospecific enzyme assay.

Propionyl-L-carnitine was converted by chemical hydrolysis (0.3 M potassium hydroxide, pH 12.8, room temperature) into L-carnitine, which competes with crotonoylbetaine formation and can be quantitatively evaluated by an enzyme assay. Under the conditions selected, hydrolysis of propionyl-L-carnitine to L-carnitine was completed in a few minutes with less than 0.5% of crotonoylbetaine being formed. The method described is enantioselective and possesses the analytical requirements for assaying propionyl-L-carnitine during chemical synthesis procedures and in pharmaceutical formulations.

Animals↗
PubMed1988

High-performance liquid chromatographic evaluation of salicyloyl pyridixol and systemic metabolites in biological samples.

An high-performance liquid chromatographic analytical method, which allows quantitative evaluation of both salicyloyl pyridixol and its metabolite salicylic acid, is reported. This method has demonstrated to possess the required specifications in terms of linearity, sensitivity, extraction recovery, reproducibility and specificity for pharmacokinetic investigations in both human subjects and experimental animals. The results obtained from an investigation on the rat are briefly discussed.

Animals↗
PubMed1988

Ultrastructural localization of IgE in peripheral blood monocytes from atopics.

Monocyte-enriched preparations derived from peripheral blood leukocytes of atopics were probed via a cocktail comprising peroxidase-conjugated (Fab1)2 fragments of two monoclonal antibodies against human IgE. Reaction product indicative of intracellular IgE was identified by electron microscopy in both large and small vacuoles, and at high magnification exhibited a characteristic granular deposition pattern consistent with highly concentrated (perhaps insolublized) material. IgE-containing vacuoles were observed with comparable frequency to those containing IgG, despite the greater than 10,000-fold relative excess of the latter in serum suggesting highly selective uptake of IgE by the monocytes. These results are similar to those reported recently for IgA in human milk macrophages.

Antibodies, Monoclonal↗
PubMed1987

Bioavailability of indomethacin from a modified release system containing indomethacin as the lysine salt.

The bioavailability of a new controlled release formulation of indomethacin lysine salt in tablets was tested in 6 healthy humans against a conventional indomethacin lysinate formulation in capsules. Both contained 100 mg of the drug, i.e. 70 mg indomethacin. Peak plasma levels were lower and more lasting and the AUC was higher with the new controlled release formulation. The latter on average produced active plasma levels for 12 h, and so it can be recommended for twice daily administration.

Biological Availability↗