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Biomedical subjects

G Gatti

Publications and source records attributed to G Gatti.

At least 235 records · Page 13Linked to original sources
PubMedDate not supplied

Pharmacokinetics of oxiracetam following intravenous and oral administration in healthy volunteers.

The kinetics of oxiracetam after single intravenous and oral doses (2000 mg) were investigated in four healthy volunteers. Following intravenous administration, the decline in serum levels showed a prolonged, rapid phase followed by a delayed terminal phase. Mean residence times ranged from 3.9 to 6.5 h. Volumes of distribution ranged from 0.9 to 1.81 X kg-1, whereas clearance values ranged from 100 to 119 ml X h-1 X kg-1 More than 90% of the intravenous dose was recovered unchanged in the urine within 48 h. Oral administration resulted in peak levels within 1-2 h; thereafter, the decline in serum levels showed a pattern similar to that observed after the intravenous dose--almost 50% of the oral dose was excreted in the urine within 6 h. The absolute availability of oral oxiracetam was 75 +/- 7%.

Administration, Oral↗
PubMedDate not supplied

Comparative pharmacokinetics and pharmacodynamics of eterobarbital and phenobarbital in normal volunteers.

The comparative pharmacokinetics and pharmacodynamics of single oral doses of eterobarbital (N,N'-dimethoxymethylphenobarbital, DMMP, 400 mg) and phenobarbital (200 mg) were evaluated in a double-blind study in 8 normal volunteers. Following administration of DMMP, no unchanged drug could be detected in serum. The active monomethoxymethyl metabolite (MMP) appeared rapidly in the circulation but its concentration remained generally low and declined below the limit of detection (0.5 micrograms/ml) usually before 9.5 h. Serum levels of DMMP-derived PB increased slowly and reached a peak between 24 and 48 h in most cases. One subject showed an atypical pharmacokinetic profile, characterized by relatively high levels of MMP and a delayed appearance of low levels of PB. After administration of PB, serum drug levels peaked within 1.5 h and remained, at all sampling times, higher than those observed after intake of DMMP. Compared with DMMP, PB induced greater sedative effects as assessed by visual analogue rating scale, critical flicker fusion frequency and multiple sleep latency tests.

Administration, Oral↗
PubMedDate not supplied

Pharmacokinetic studies on IdB 1016, a silybin- phosphatidylcholine complex, in healthy human subjects.

IdB 1016 is a complex of silybin (the main active component of silymarin) and phosphatidylcholine, which in animal models shows greater oral bioavailability and therefore greater pharmacological activity compared with pure silybin and silymarin. In order to assess its pharmacokinetic profile in man, plasma silybin levels were determined after administration of single oral doses of IdB 1016 and silymarin (equivalent to 360 mg silybin) to 9 healthy volunteers. Although absorption was rapid with both preparations, the bioavailability of IdB 1016 was much greater than that of silymarin, as indicated by higher plasma silybin levels at all sampling times after intake of the complex. Regardless of the preparation used, the terminal half-life was relatively short (generally less than 4 h). In a subsequent study, 9 healthy volunteers received IdB 1016 (120 mg b.i.d., expressed as silybin equivalents) for 8 consecutive days. The plasma silybin level profiles and kinetic parameters on day 1 were similar to those determined on day 8. Most of the silybin present in the systemic circulation was in conjugated form. Less than 3% of the administered dose was accounted for by urinary recovery of free plus conjugated silybin, a significant proportion of the dose probably being excreted in the bile. It is concluded that complexation with phosphatidylcholine in IdB 1016 greatly increases the oral bioavailability of silybin, probably by facilitating its passage across the gastrointestinal mucosa.

Administration, Oral↗
PubMedDate not supplied

Comparative bioavailability and tolerability study of two intramuscular formulations of thiocolchicoside in healthy volunteers.

The comparative bioavailability and tolerability of two intramuscular fomulations of thiocolchicoside (test, Thiocolchicoside, 4 mg ampoules, Dompé S.p.A.; reference, Muscoril, 4 mg ampoules, Inverni della Beffa S.p.A.) were investigated in twelve healthy volunteers according to a single dose (4 mg), cross-over, randomized design. Plasma thiocolchicoside concentrations were determined by using a validated specific HPLC/MS assay and local tolerability was investigated by assessing subjective pain intensity on a visual analogue scale (VAS), reddening at the injection site, and plasma creatinine phosphokinase (CPK) levels. Pharmacokinetic parameters after administration of the test formulation were similar to those observed after administration of the reference (Tmax 0.50 (0.25-1.00) vs 0.50 (0.25-1.00), median and range; Cmax 115.5 +/- 26.6 vs 113.2 +/- 40.4 ng/ml; AUC 291.6 +/- 77.7 vs 283.3 +/- 98.9 ng.h/ml, means +/- SD). Relative bioavailability (F) was 1.05 +/- 0.13. Statistical comparison of pain intensity, CPK levels and occurrence of redness at the injection site did not show statistically significant differences between formulations. It is concluded that the investigated test formulation is bioequivalent and equally well tolerated as the marketed reference formulation.

Adult↗
PubMedDate not supplied

Involvement of Ca2+-dependent pathways in the inhibition of human natural killer (NK) cell activity by cortisol.

The role of Ca2+ as a second messenger of the glucocorticoid inhibition of human natural killer (NK) cell activity was evaluated using Ca2+ entry blockers (verapamil and its desmethoxy derivatives LU46973 and LU47093), calmodulin antagonists (pimozide and two naphthalensulfonamide derivatives, W-7 and W-13), the Ca2+ channel agonist BAY K 8644 and the calcium ionophore A23187. Peripheral blood mononuclear (PBM) cell preparations were incubated for 20 h with 1 x 10(-6) M cortisol and these agents in various combinations (concentration range: 1 x 10(-9) -1 x 10(-5) M) and then assayed in a direct 4-h cytolytic assay using 51Cr-labeled K 562 target cells. Exposure to cortisol led to a significant reduction of NK cell activity (about 50% vs. spontaneous activity). Ca2+ entry blockers and calmodulin antagonists were per se minimally effective, but significantly enhanced cortisol-dependent inhibition of NK cell activity. Raising extracellular Ca2+ by CaCl2 or intracellular Ca2+ by the calcium channel agonist BAY K 8644 or the ionophore A23187 resulted in an appreciable reduction of these effects. Similar results were obtained when these substances were added to monocyte-depleted or NK cell-enriched suspensions exposed to cortisol. Our data are consistent with the view that extra- and intracellular Ca2+ plays a role in the control of human NK cell activity. It is also conceivable that both calcium flux into the cell and the calcium calmodulin system are involved in the cortisol-induced inhibition of natural cytotoxicity.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMedDate not supplied

Erythromycin resistance in Streptococcus pyogenes in Italy.

In a prospective study of acute pharyngitis in Italian children, 69 (38.3%) of 180 isolates of Streptococcus pyogenes were resistant to macrolides. S. pyogenes was eradicated in 12 (63.1%) of 19 patients with erythromycin-resistant S. pyogenes treated with clarithromycin and in 22 (88%) of 25 patients with erythromycin-susceptible strains. The constitutive-resistant phenotype was correlated with failure of macrolide treatment.

Adolescent↗
PubMedDate not supplied

[Epidemiological observations on plasma levels of diphenylhydantoin in 130 patients on prolonged treatment (author's tranls)].

Plasma levels of diphenylhydantoin have been measured in 130 epileptic patients undergoing long-term anticonvulsant therapy. Only in a small percentage of the patients (15,38%) plasma levels were found to lie within the therapeutic range. Most patients (75,38%) exhibited subtherapeutic values, while in a few cases (9,24%) the upper limit of therapeutic range was exceeded. Although plasma concentrations significantly correlate with the administered dose, predictability of plasma levels in the individual patients given fixed dosage schedules is strongly limited by large interindividual variability. Sex, age and simultaneous administration of other drugs seem not to affect significantly DPH plasma levels. Our observations carried out in a meaningful sample of epileptic patients suggest that at present the practice of monitoring diphenylhydantoin plasma levels is still an essential tool for the management of epilepsy when a safe and effective therapeutic regimen is required.

Epilepsy↗