Differential effects of alpha-adrenoceptor blockade on essential, physiological and isoprenaline-induced tremor: evidence for a central origin of essential tremor

Intravenous thymoxamine reduced the power of essential tremor but increased that of physiological and isoprenaline-induced tremor. These findings indicate that essential and physiological tremor have dissimilar pathophysiological mechanisms. They also suggest that central adrenergic mechanisms are involved in the pathophysiology of essential tremor and that isoprenaline-induced tremor is not a good model of essential tremor. Furthermore, alpha-adrenoceptor blockers may be a useful therapy for essential tremor.

[The effect of antiglaucoma drugs on the depth of the anterior chamber (I)]

The Authors have taken into account the most common effect of antiglaucomatous drugs on the depth of the anterior chamber. The modifications of the anterior chamber have been evaluated utilizing a Jaeger Pachymeter. The values were obtained before the drug instillation and an hour afterwards. The results are presented as the mean and standard deviation. Among the examined drugs, only miotics have brought about a notable decrease, whereas the others have shown no significant effects.

Reduction of systemic vascular resistance by competitive alpha adrenergic blockage with thymoxamine after cardiopulmonary bypass for cardiac operations

Fifteen patients with evidence of excessive systemic vasoconstriction following cardiac operations were studied. Serial hemodynamic measurements were made before and during infusion of thymoxamine, a competitive alpha adrenergic blocking drug. Thymoxamine resulted in a full in systemic resistance together with a rise in cardiac index without reflex tachycardia. When thymoxamine was infused at a rate of 1 mg . kg-1, the desired effect was achieved without sudden profound falls in arterial pressure and there were no significant side effects. During the first few hours after bypass, skin temperature measurements do not give an adequate indication of the circulatory state. Measurement of mixed venous oxygen saturation is a most useful, simple method of monitoring the acute effects of treatment during this period.

Thymoxamine hydrochloride: an alpha-adrenergic blocker

Thymoxamine is an alpha-adrenergic blocking agent which works by competitive antagonism of norepinephrine. It is the only alpha-adrenergic blocker available which has tolerable side effects when used as an ophthalmic solution. When used as a 0.5% solution it consistently produces miosis without affecting the intraocular pressure or the ciliary muscle-controlled facility of outflow. The only regularly reported side-effects at this concentration are transient burning and conjunctival hyperemia. Potential applications of thymoxamine include reversal of phenylephrine mydriasis, treatment of angle-closure glaucoma, treatment of persistent mydriasis after penetrating keratoplasty for keratoconus, reversal of lid retraction in thyroid ophthalmopathy, testing to differentiate angle-closure glaucoma from open-angle glaucoma with narrow angles, aiding in repositioning and maintaining the position of intraocular lenses, treatment of pigmentary glaucoma. Thymoxamine may also contribute to a better understanding of the adrenergic nervous system on aqueous dynamics.

Case report of ?hormonal vertigo

A case-history of episodic vertigo, extending over 25 years, is reported. This case was twice investigated from the neurological standpoint without a definite conclusion being reached. Eventually a hormonal-electrolyte disturbance was postulated and, to some extent, established by prolonged observation and treatment.

Effect of thymoxamine in the relief of pain and rate of healing in ischaemic leg ulceration

A small uncontrolled pilot study was carried out in 6 patients with ischaemic leg ulceration in which pain was severe to assess the effectiveness of thymoxamine in the relief of pain and on the rate of healing. Patients were treated for 3 days with intravenous injections of 0.1 mg thymoxamine/kg body weight and then with oral 40 mg thymoxamine 4-times daily for a further month. The results showed that there appeared to be a definite improvement in pain during intravenous therapy and this was maintained to a large extent, although not so definite, on oral therapy. No enhanced rate of healing, however, was evident.

The use of thymoxamine in eyelid retraction

We observed substantial narrowing in 75% of fissures in patients with various types of lid retraction after topical application of aqueous 0.5% thymoxamine (moxisylyte). Even contralateral normal-appearing fissures in thyroid patients responded in this manner. The nonresponders in the lid retraction group included a patient with an orbital pseudotumor and patients with long-standing and stable euthyroid eye disease. No normal subjects' fissures responded greatly to thymoxamine. A substantial reduction in palpebral fissures was seen in all patients with thick extraocular muscles and in 14 of 18 (78%) of all fissures of thyroid patients; the average response was 2.3 mm. This effect may last for five hours after thymoxamine administration. Thymoxamine may be of use as a diagnostic test for thyroid eye disease, and if it can be modified to cause less ocular irritation, it may be beneficial in the medical treatment of eyelid retraction.

The effects of thymoxamine on anterior chamber depth in human eyes

The effects of 0.5% Thymoxamine on intraocular pressure and anterior chamber depth were studied in 20 non-glaucomatous eyes. Miosis occurred in all of the eyes but was not accompanied by a shallowing of the anterior chamber or reduction in the intraocular pressure. The significance of the findings is discussed.

Thymoxamine test. Differentiating angle-closure glaucoma form open-angle glaucoma with narrow angles

To help differentiate mild angle-closure glaucoma from open-angle glaucoma in patients with elevated intraocular pressure (IOP) and angles so narrow that the structures cannot be seen adequately, we used a thymoxamine hydrochloride eyedrop that induces miosis and tends to widen the angle. Thymoxamine does not contract the ciliary muscle and does not alter the IOP or facility of outflow in open-angle glaucoma, but it can relieve angle-closure glaucoma. A test with thymoxamine was performed in 26 patients because of this differential diagnostic dilemma. When gonioscopic, tonometric, and tonographic findings appeared to indicate a diagnosis of angle-closure glaucoma, a peripheral iridectomy was done. Subsequent (one to 27 months) observations have substantiated that testing with thymoxamine is a helpful aid in this differential diagnosis, and merits more widespread evaluation.

Retrospective assessment of thymoxamine (Opilon) in treatment of Ménières disease

A retrospective study of 305 patients treated with thymoxamine (Opilon) for Ménières disease is described. Thymoxamine controlled symptoms in 78.7% of patients and the time to maximum improvement ranged from six weeks to three months. Seven patients suffered side-effects.

Depression of spasticity by alpha-adrenergic blockade

In spastic patients the alpha-adrenergic blocking drug thymoxamine (Opilon Forte) was found capable of depressing most propioceptive reflex parameters within 1 min after intravenous administration. The action seems to be of CNS origin, probably exerted as a depression of spindle stretch sensitivity through descending alpha-adrenergic bulbospinal pathways, but an additional action on the mechanism of presynaptic inhibition is likely. With oral administration, the drug is also capable of depressing distressing clonus, and it is concluded that it deserves further testing as a spasmolytic.

Thymoxamine and intraocular pressure

Topical treatment with 1% thymoxamine produces in rabbit and human eyes a small but real miotic and tension-lowering effect. The latter is more evident using two different models of experimental ocular hypertension in rabbits. In human open-angle glaucoma eyes, tonographic measurements indicate that the outflow facility is left unchanged by the drug.

Effect of alpha receptor blocking drug, thymoxamine, on allergen induced bronchoconstriction in extrinsic asthma

In ten patients with extrinsic bronchial asthma, allergen provoked bronchospasm was significantly inhibited by the alpha receptor blocking drug thymoxamine given intravenously. In two of these patients thymoxamine by inhalation also effectively inhibited allergen induced bronchoconstriction. It is suggested that thymoxamine may be acting either by increasing intracellular levels of cyclic AMP and thus inhibiting mediator release following allergen challenge or by modifying the airways response to these mediators by altering the bronchomotor tone. The variable responses recorded after allergen challenge in presence of alpha blockade with thymoxamine suggests that the dominant effect is on the bronchomotor tone rather than the mediator release.