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Biomedical subjects

S D Vakil

Publications and source records attributed to S D Vakil.

18 recordsLinked to original sources
PubMed1999

Lack of a pharmacokinetic interaction at steady state between ropinirole and L-dopa in patients with Parkinson's disease.

STUDY OBJECTIVE: To assess the interaction between therapeutic dosages of ropinirole and L-dopa plus a decarboxylase inhibitor administered at steady state in patients with Parkinson's disease. DESIGN. Open, 6-week, overlap trial with random allocation. PATIENTS: Thirty patients with Parkinson's disease not previously treated with dopamine agonists, of whom 28 produced evaluable pharmacokinetic data for ropinirole and 23 for L-dopa. INTERVENTION: Group A (14 patients) received L-dopa for weeks 1-5 and ropinirole in increasing increments for weeks 2-6; group B (16) received ropinirole for weeks 1-5 and L-dopa for weeks 5 and 6. MEASUREMENTS AND MAIN RESULTS: Primary end points were AUC0-8 and Cmax for ropinirole, and AUC0-8, AUC0-infinity and Cmax for L-dopa. Secondary end points were Tmax for ropinirole, and Tmax and half-life for L-dopa. Coadministration with L-dopa at steady state did not affect rate or extent of availability of ropinirole: point estimates of the geometric mean ratio for ropinirole plus L-dopa compared with ropinirole alone for both Cmax and AUC0-8 approximated to unity. The small (16%) increase in peak concentrations of L-dopa on administration with ropinirole is unlikely to be of clinical consequence, as peak concentrations of L-dopa are typically highly variable. CONCLUSION: There are no pharmacokinetic grounds for adjusting dosages of either ropinirole or L-dopa when given in combination.

Aged↗
PubMed1982

Toxoplasma, Toxocara, and epilepsy.

The presence of positive antibody titres to Toxoplasma and Toxocara in an adult epileptic population has been examined in relation to other observations of aetiological importance. With Toxoplasma, and more particularly with Toxocara, a higher incidence of positive antibody titres was recorded than in nonepileptic populations. Comparison with previous studies in childhood epilepsy indicate that the incidence of positive titres increased with age throughout adult life. Despite attention to the age of onset of epilepsy, presumed aetiological factors, and electroencephalographic and clinical observations, no causal relationship between parasitic infection and the aetiology of epilepsy was established.

Antibodies↗
PubMed1976

Dupuytren's disease in epilepsy: result of prolonged administration of anticonvulsants.

In a study of chronic epileptics in a residential centre we recorded a 56% incidence of Dupuytren's disease. The lesions were usually bilateral and symmetrical and frequently associated with knuckle pads and plantar nodules. There was no direct relationship between Dupuytren's disease and frozen shoulder. Dupuytren's disease was seen equally in those with idiopathic or symptomatic epilepsy. The incidence increased with the duration of epilepsy and is probably a sequel to long-term administration of phenobarbitone. Reasons are given for presuming that the association between Dupuytren's disease and antiepileptic therapy is mediated through the peripheral stimulation of tissue growth factors and not through the central release of growth hormone or through alterations in liver metabolism.

Adult↗
PubMed1975

Arterial blood pressure in patients with Parkinson's disease.

The casual arterial blood pressure of 411 patients with Parkinson's disease was compared with that of a representative sample of the general population. The patients were also divided into various sub-groups, and comparisons of blood pressure were made between them. The results provided no support for the widely held belief that blood pressure tends to be low in patients with Parkinson's disease.

Adult↗
PubMed1972

Action of L- -methyldopa-hydrazine on the blood pressure of patients receiving levodopa.

The blood pressure and pulse rate have been compared in a 'double blind, cross over' study involving twenty patients with idiopathic Parkinsonism receiving maximum tolerated dosage of levodopa with and without an extracerebral decarboxylase inhibitor, L-alpha-methyldopahydrazine. The supine and erect systolic pressures were significantly higher and the erect pulse rate significantly lower during administration of L-alpha-methyldopahydrazine. The implications of these observations are discussed.

Adult↗
PubMed1971

Idiopathic Parkinsonism treated with an extracerebral decarboxylase inhibitor in combination with levodopa.

The clinical actions of levodopa in Parkinsonism, given with and without an extracerebral decarboxylase in hibitor, L-alpha-methyldopahydrazine, were compared. Twenty-one patients were investigated in a "double-blind cross-over" study, administering levodopa in maximum tolerated dosage. L-Alpha-methyldopahydrazine failed to augment the overall therapeutic actions of levodopa but it consistently alleviated nausea. It is concluded that L-alpha-methyldopahydrazine will prove useful in the management of some Parkinsonian patients who have difficulty in taking levodopa alone.

Adult↗
PubMed1971

Action of thymoxamine on mydriasis induced by levodopa and dopamine.

Eye-drops of levodopa and dopamine induce pupillary dilatation which is inhibited by thymoxamine, an alpha-adrenergic blocking drug. This indicates that the mydriatic action of levodopa and dopamine involves excitation of alpha-adrenergic receptors of the dilator pupillae muscle. Such a conclusion is in accord with the previously expressed suggestion that levodopa is rapidly converted to dopamine, which displaces noradrenaline from adrenergic nerve endings.The findings that dopamine exerts alpha-adrenergic effects at the periphery may be construed as evidence in support of the view that the hypotensive action of levodopa is mediated via the central nervous system.

Adrenergic alpha-Antagonists↗