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Biomedical subjects

M Virno

Publications and source records attributed to M Virno.

At least 19 recordsLinked to original sources
PubMed1993

Ocular pharmacokinetics and pharmacodynamics in rabbits of ibopamine, a new mydriatic agent.

Ibopamine is an original dopamine analogue. The drug, instilled in the conjunctival sac, induces mydriasis and is well-tolerated. In the present study, we have investigated the pharmacokinetic and pharmacodynamic characteristics of ibopamine after ocular application. Ibopamine produces a dose-dependent mydriasis endowed with very interesting characteristics: rapid onset, marked pupil dilation and rapid return to normal pupillary diameter. Ibopamine is well absorbed through the cornea, it is rapidly hydrolysed by esterases to epinine and the mydriatic effect is correlated with the concentration of epinine in the aqueous humor. The results of the experiments with the alpha 1-antagonists bunazosin and thymoxamine, and with reserpine, suggest that the mydriatic effect of ibopamine is obtained by direct stimulation of the alpha 1-adrenergic receptors; pretreatment with bunazosin almost completely inhibits the mydriatic activity of ibopamine; the mydriasis is also antagonized by thymoxamine. Pretreatment with reserpine has no effect on the extent of the mydriasis induced by ibopamine.

Adrenergic alpha-Agonists↗
PubMed1992

Brain oedema and intracranial hypertension treatment by GLIAS.

The authors present their results regarding the use of a buffered solution of glycerol 30%-sodium ascorbate 20% (GLIAS) for the treatment of brain oedema and intracranial hypertension. GLIAS was perfused intravenously in 80 patients with several types of brain oedema. In every patients serum and urinary osmolarity, diuresis, main blood and urine parameters, and ICP were monitored. Following GLIAS infusion an increase in plasma osmolarity was observed, changing the average basal value plus 13.4% after 15 min., 10.5% after 30'. At the same time there was a reduction of ICP and improvement in cerebral compliance. In each case there was a decrease in intracranial hypertension and brain oedema without significant collateral effects.

Adolescent↗
PubMed1992

Dopamine, dopaminergic drugs and ocular hypertension.

The study refers to the clinical experiences performed with several D1 and D2 dopaminergic receptors agonists in 20 patients with high tension open angle glaucoma. The substances were administered topically as eye drops as well as an ocular eye bath. The parameter examined was intraocular pressure (IOP). The substances taken in consideration were: Dopamine, Ibopamine (dopamine analog), Fenoldopam and 3B90 (D1-receptor agonists) and Bromocriptine (dopaminergic agonist with higher affinity for D2 than for D1-receptors). It has been shown that all selective D1-receptors agonists induce a significant increase in IOP only in eyes with hydrodynamic disorders (p < 0.001). Such hypertensive effects could not be antagonized either by topically administered dopaminergic antagonists (Sulpiride, D2-receptors antagonist, and Haloperidol, non-selective dopaminergic antagonist) or by the pretreatment with the commonly used topical antiglaucomatous drugs. The only substance which proved able to inhibit the IOP increase induced by the D1-receptors agonists was the D1-selective antagonist SCH-23390, suggesting that IOP increase may be a result of a stimulation of the D1-receptors. The authors hypothesize that dopaminergic system may play a role in the regulation of aqueous humor hydrodynamics.

Adult↗
PubMed1991

[The mechanism of cholinergic effects on lowering intraocular pressure].

The relationship between vasomotoric activity and blood vessel permeability was studied in the course of discovering the ocular hypotonising mechanism of cholinergic drug activity (pilocarpin and carbamylcholin). The authors found, in experimental conditions, that the vasomotoric activity (vasodilatation) of the two cholinergic drugs is expressed in the increased permeability of the blood-aqueour barrier. In the presence of an elevated extracirculatory pressure (IOP), as in glaucoma, vasodilatation under the influence of cholinergic drugs, is converted to passive vasoconstriction which leads to reduced aqueous humor production. Carbamilcholin reduces aqueous humor production in a greater extent than pilocarpin.

Animals↗
PubMed1989

Therapeutic value of citicoline in the treatment of glaucoma (computerized and automated perimetric investigation).

The favourable neurotrophic effects obtained by means of the intramuscular administration of citicoline, one of the intermediate compounds of phospholipids, on the visual field of patients suffering from open-angle glaucoma are referred. The drug was administered at the dose of 1 gm for ten consecutive days. Visual field was examined by means of central computerized perimetry and automated perimetry. All patients had well controlled intraocular pressure through beta-blockers, but presented characteristic glaucomatous perimetric defects. It is suggested that citicoline might be administered as a useful complement to conventional hypotensive therapy, since it acts positively on the glaucomatous optic nerve damage.

Adult↗
PubMed1983

[The alpha-adrenergic effect of thymoxamine on the vessels of the ciliary body].

The effects of epinephrine on the permeability of the blood-aqueous barrier, stimulated by paracentesis of the anterior chamber, were studied in rabbits following alpha-adrenergic blocking by means of topical or systemic thymoxamine. The alpha-adrenergic block was tested by continuous recording of the systemic arterial blood pressure. The reversal of the vascular effects of epinephrine after administration of thymoxamine was demonstrated at the bloodaqueous barrier. The miotic property of thymoxamine is believed to have had no influence on our results.

Animals↗