Specific Medicinal Uses of Cannabis: Glaucoma

Cannabis smoking and the oral ingestion of several of its derivatives have been shown to cause an appreciable drop in intraocular pressure (); and it is known that patients with open angle closure glaucoma smoke cannabis for this purpose. Cannabis When smoked, cannabis containing the equivalent of 20–30 mg of THC has been shown to lower intraocular pressure in an heterogeneous group of glaucoma patients and more specifically, patients with open angle glaucoma. However, the treatment was not without side effects: six of 32 patients developed severe systemic hypotension; this was significantly greater in hypertensive glaucoma patients. Cannabis caused a dose-related, clinically significant, reduction in intraocular pressure of 25– 30%, occurring at 1 hour and lasting 5–6 hours, which was discrete from the sedative effects of the drug. Orthostatic hypotension was observed mainly in cannabis-naive patients. Cannabis does not cure glaucoma but has been shown to slow progressive sight loss when conventional medicines have failed or where the risks of surgery are too great. Tolerance to this effect of cannabis has not been observed; but the degree of reduction in intraocular pressure seen in cannabis-naive patients Read more […]

ANTISYMPATHETIC AGENTS

ANTISYMPATHETIC AGENTS is a grouping of convenience intended to encompass all agents acting by one of the many mechanisms that lead to a reduction in the actions of the sympathetic nervous system, including those of poorly defined mechanism that are known to have this overall action. Antisympathetics are of particular importance in reducing vasomotor tone, and thence blood pressure. There are many of them and they will be grouped by site and mechanism of action. See also ANTIHYPERTENSIVE AGENTS. Central mechanisms. Some agents may act within the CNS to modify autonomic control of sympathetic tone and blood pressure. Clonidine inhibits release of noradrenaline by an agonist action at the autoinhibitory alpha2-adrenoceptors on sympathetic nerve endings. Methyldopa is thought to work, at least in part, centrally, acting both as an inhibitory false substrate in the biosynthetic pathway, also producing an active metabolite with actions at α2-adrenoceptors. Rauwolfia alkaloids, especially reserpine, which inhibit the monoamine transporters, were at one time used to treat hypertension, but the side-effects are marked. Biosynthetic pathway inhibitors. In both the central and periphery nervous systems, the biosynthetic Read more […]

β-ADRENOCEPTOR ANTAGONISTS

β-ADRENOCEPTOR ANTAGONISTS (also known as β-adrenergic receptor blocking drugs, β-adrenoceptor blocking drugs or beta-blockers) are drugs that inhibit certain actions of the sympathetic nervous system by blocking the action of adrenaline and noradrenaline (catecholamine mediators acting predominantly as hormone or neurotransmitter respectively). Among other actions, β-adrenoceptors have cardiac stimulant actions, they dilate certain blood vessels, suppress motility within the gastrointestinal tract, stimulate certain aspects of metabolism causing an increase in glucose and free fatty acids in the blood. These actions, in concert with those of the α-adrenoceptors, help prepare the body for emergency action. However, in disease, some of these effects may be inappropriate, exaggerated and detrimental to health, so β-blockers may be used to restore the balance. Thus β-blockers are used to lower blood pressure when it is abnormally raised in cardiovascular disease (see ANTIHYPERTENSIVE AGENTS): to correct certain heartbeat irregularities and tachycardias (see ANTIARRHYTHMICS); to prevent the pain of angina pectoris during exercise by limiting cardiac stimulation (see ANTIANGINALS)’, to treat myocardial infarction, Read more […]

ANTIMIGRAINE DRUGS

ANTIMIGRAINE DRUGS are used to treat migraine attacks, which constitute a specific clinically recognized form of headache. Attacks vary in form, but common characteristics include: throbbing in the head confined to one side only (unilateral headache), nausea and vomiting, and a forewarning of the attack (an aura) consisting of visual disturbances and weakness or numbness of the limbs. Drugs are used to help migraine sufferers (and the related state called ‘cluster headache‘) in two quite distinct ways. One group of drugs is given chronically, and helps to prevent attacks (prophylactic use): such as CALCIUM-CHANNEL BLOCKERS. e.g. nifedipine and verapamil; the β-blockers, e.g. metoprolol, nadolol, propranolol and timolol (see β-ADRENOCEPTOR ANTAGONISTS); and also certain vasoactive drugs, including cyproheptadine and the ergot alkaloid methysergide. All these drugs affect blood vessels. In migraine attacks, cerebral vessels are thought to constrict before an attack, then dilate, causing pain during the attack. A second group of drugs may be used to treat acute attacks, either at the stage of the prewarning aura, or during the attack stage itself; and here speed of administration and subsequent absorption of the Read more […]

ANTIANGINAL AGENTS

ANTIANGINAL AGENTS are used to relieve angina pectoris, an intense pain due to cardiac ischaemia, which is especially pronounced in exercise angina. The disease state often results from atheroma; a degeneration of the lining of the arteries of the heart due to build-up of fatty deposits. The objective is to relieve the heart of work, and to prevent spasm or to dilate coronary arteries. Unloading can be achieved by stopping exercise, preventing the speeding of the heart and by dilating the coronary arteries. Beta-blockers, by inhibiting the effect of adrenaline and noradrenaline on the heart, prevent the normal increase in heart rate, and are very effective in preventing exercise angina. Examples of beta-blockers used for this purpose include acebutolol, atenolol, metoprolol, nadolol, oxprenolol, pindolol, propranolol, sotalol and timolol. See β-ADRENOCEPTOR ANTAGONISTS. Many VASODILATORS act directly to relax vascular smooth muscle, so dilating blood vessels and thereby increasing blood flow (see SMOOTH MUSCLE RELAXANTS). For the acute treatment of anginal pain (and to a lesser extent in preventing angina attacks) the nitrates are widely used, e.g. glyceryl trinitrate, isosorbide dinitrate, isosorbide mononitrate Read more […]