Clonidine for migraine

Clonidine in neuropsychiatric disorders: a review

We describe the basic pharmacological principles underlying the activity of the alpha 2-adrenergic receptor agonist clonidine, including its interactions with the cholinergic, histaminergic, serotoninergic, endorphinergic and possibly dopaminergic systems. The use of clonidine for the therapy of various neuropsychiatric indications in which it appears to be beneficial is described. These conditions include migraine, Korsakoff's psychosis, Tourette's syndrome, withdrawal states, tardive dyskinesia, essential tremor, neuroleptic-induced akathisia, neurogenic bladder, idiopathic orthostatic hypotension, paroxysmal localised hyperhydrosis, diabetic neuropathy and stiff-man syndrome. The need for long term evaluation of this agent in some of these diseases is stressed.

Metoprolol v. clonidine in the prophylactic treatment of migraine

In a double-blind, cross-over trial, the migraine prophylactic effect of the beta 1-adrenoceptor antagonist metoprolol was compared with that of clonidine. The dosage of metoprolol was 50 mg b.i.d. and of clonidine 50 micrograms b.i.d. Thirty-one patients were included; twenty-three completed the entire study. Six patients withdrew during clonidine treatment, one during metoprolol treatment and one during the wash-out period (placebo). Metoprolol had a significantly better migraine prophylactic effect than clonidine regarding such parameters as the attack frequency, the number of migraine days and the sum of intensity score. Compared to baseline (placebo), metoprolol decreased these parameters, while clonidine did not. Metoprolol, but not clonidine, also reduced the acute consumption of analgesics. No differences were found as regards side effects.

Isolation and partial purification of a clonidine-displacing endogenous brain substance

A new compound, designated clonidine-displacing substance (CDS), has been isolated from calf brain by ion-exchange chromatography, zone electrophoresis and high-performance liquid chromatography. CDS binds specifically to alpha 2-adrenergic receptors in rat brain and human platelet membranes, as measured in direct binding experiments using [3H]clonidine and [3H]yohimbine respectively. Unlike clonidine or other alpha 2-agonists, CDS does not affect basal levels of adenylate cyclase in human platelets at the highest concentrations obtainable. The apparent molecular mass of the compound is estimated to be 500 +/- 50 Da, as determined by gel-filtration chromatography on Sephadex G-15. The new compound is thermostable, not affected by proteolytic enzymes, such as trypsin, chymotrypsin, pronase, papain and pyroglutamase, or by boiling in 0.2 M HCl for 5 min. It does not bind to alpha 1-receptors in rat brain or to beta-adrenergic receptors in turkey erythrocytes, since it is unable to displace [3H]prazosin and [125I]cyanopindolol from alpha 1 and beta-receptors respectively.

Studies with clonidine (dixarit) in menopausal women

Eleven women with menopausal symptoms were treated with 150 micrograms Clonidine (dixarit) daily. Before and during therapy, plasma estradiol-17 beta, LH, FSH and prolactin levels were measured by specific radio-immunoassays. In addition, each patient recorded the number of hot flushes a day and symptoms were monitored by the Kupperman-index. A highly significant fall in the number of hot flushes by day and night occurred during therapy (p less than 0.001) and the Kupperman-index similarly improved. Significant pulse and blood pressure changes were not noted and plasma hormone concentrations remained unaltered. Medication was well tolerated. Clonidine therapy would appear to be the treatment of choice for menopausal symptoms if estrogens are contraindicated.

Clonidine in the treatment of menopausal symptoms

Thirty-seven women complaining of hot flushes, sweating and other menopausal symptoms were treated with clonidine. A double-blind crossover trial with placebo controls was undertaken. The clonidine dose was 2 X 0.025 mg/24 hours-0.075 mg/24 hours, increased if necessary at intervals of two weeks. The effect of clonidine did not differ significantly from placebo effect in the treatment of the symptoms. Side effects during clonidine management were slight and no difference was seen in their incidence compared with that in the patients treated with the placebo. A definitive placebo response was perceivable in the decreasing of symptoms.

Clonidine in the prophylaxis of migraine

The prophylactic effect of clonidine in a dosage of 0.05 mg twice daily was investigated in 49 patients using a double-blind, crossover trial carried out in four Departments of Neurology. Seventy-one patients were originally included but 22 patients withdrew, two of them due to side effects,the remainder because of inability to keep the requisite diary, lack of drug compliance or refusal to attend the checkups. Approximately equal numbers withdrew during the clonidine and placebo periods. There was no statistically significant difference between the number of migraine attacks or between the number of severe attacks (8 hours' duration or more) during the placebo and clonidine periods. This also applied to the patients with foodstuff-provoked migraine attacks. Sixty-three patients carried through a double-blind, crossover trial with capsules containing either 125 mg tyramine or placebo. There was no significant difference between the number of patients who developed attacks after the ingestion of placebo and the number who did so after the ingestion of tyramine. The same is true of the group with foodstuff-provoked migraine. As a rule side effects were few and mild. This study has not confirmed that clonidine has any pharmacological effect in prophylaxis of migraine.

Failure of response of menopausal vasomotor symptoms to clonidine

A double-blind crossover trial of clonidine failed to show any effect of the drug on menopausal vasomotor symptoms. A significant placebo effect was observed, the effect being greater in those with long-standing symptoms and a high neurotic index.

Migraine and the blood-brain barrier

The prodromal (cerebral) symptoms of migraine are associated with a fall in cerebral blood-flow (C.B.F.). The suggestion that various circulating vasoactive agents might be the cause of this fall in C.B.F. ignores the contradictory findings that the cerebral vascular bed is normally unresponsive to such agents; but if the blood-barrier is disrupted, systemically administered monoamines and prostaglandins elicit pronounced changes in cerebral-tissue perfusion and metabolism. A defect in the blood-brain barrier of migraine patients (particularly those in whom an item of diet may trigger an attack) would make the cerebral circulation vulnerable to variations in circulating levels of vasoactive substances. Alternatively, the barrier could be intact in non-dietary patients, but release of monoamines or prostaglandins from the brain itself could account for the observed changes in the cerebral circulation.

Amitriptyline in migraine prophylaxis. Changes in pattern of attacks during a controlled clinical trial

A double-blind controlled clinical trial of crossover design was conducted in 26 volunteers suffering from migraine. Of 20 subjects who completed the trial, 16 had fewer attacks on amitriptyline than on placebo. Amitriptyline was found to have the greatest effect in reducing attacks with a short warning and in which no specific cause could be recognized. It had least effect in attacks with a long warning and recognized as due to fatigue. The drug was effective only in reducing those attacks with shorter duration and its effect was irrespective of severity. A dosage of between 10 and 60 mg, usually taken at night, was found to be adequate.

An assessment of platelet aggregation induced by 5-hydroxytryptamine

A method of expressing platelet aggregation response after incubation relative to the response before incubation has been used in preference to using direct measurements, and some reasons are given for this choice. The effect of pre-incubating human platelets with reserpine has been compared with the effect of pre-incubation with 5-hydroxytryptamine (5HT). Reserpine inhibited 5HT-induced aggregation more slowly than 5HT and on this basis their actions could be distinguished. It was found that the aggregation response of human platelets to 5HT without pre-incubation (R) is inversely proportional to the natural 5HT content of whole blood, and an explanation has been suggested.A decrease in the aggregation response of human platelets to 5HT without pre-incubation (R) with increasing age has been noted, and is commented upon with reference to the release of amines from blood platelets. Platelets in plasma obtained from control subjects and incubated with methysergide and from migrainous patients taking methysergide both have reduced aggregation responses to 5HT. Platelets incubated with clonidine (St155) do not have reduced aggregation responses. A potentiating effect was noted after 20 minutes' incubation, but platelets from migraine patients taking St155 behaved normally. Tyramine affected the response of platelets to 5HT, giving results similar to those reported for reserpine. The differences between the aggregation responses to 5HT of platelets from migraine patients and normal control subjects are discussed.