Antimuscarine Health Dictionary

Antimuscarine: From 1 Different Sources


A pharmacological e?ect where the action of ACETYLCHOLINE, a chemical neurotransmitter released at the junctions (synapses) of parasympathetic and ganglionic nerves, is inhibited. The junctions between nerves and skeletal muscles have nicotinic receptors. A wide range of drugs with antimuscarinic effects are in use for various disorders including PSYCHOSIS, BRONCHOSPASM, disorders of the eye (see EYE, DISORDERS OF), PARKINSONISM, and problems of the GASTROINTESTINAL TRACT and URINARY TRACT. (See also ANTISPASMODICS.)
Health Source: Medical Dictionary
Author: Health Dictionary

Antispasmodics

These are antimuscarinic drugs (see ANTIMUSCARINE) which have the property of relaxing smooth muscle. Along with other antimuscarinic drugs, antispasmodics may be helpful supportive treatment for patients with non-ulcer DYSPEPSIA, IRRITABLE BOWEL SYNDROME (IBS) and DIVERTICULAR DISEASE. Examples of antispasmodic drugs are ATROPINE sulphate, dicyclomine bromide and propantheline (a synthetic antimuscarinic drug used as a treatment adjunct in gastrointestinal disorders and also for controlling urinary frequency), bromide, alverine, mebervine and peppermint oil. With the arrival of more powerful and speci?c antisecretory drugs, such as the histamine H2-receptor antagonists – examples are CIMETIDINE and RANITIDINE – the use of antispasmodics has declined.... antispasmodics

Benzhexol

One of the antimuscarinic (see ANTIMUSCARINE) group of drugs used to treat PARKINSONISM. Acting by correcting the relative central cholinergic excess resulting from DOPAMINE de?ciency, the drug has a moderate e?ect, reducing tremor and rigidity but with little action on BRADYKINESIA. It has a synergistic (see SYNERGIST) e?ect when used with LEVODOPA and is useful in reducing SIALORRHOEA. Valuable in treating cases of Parkinsonian side-effects occurring with neuroleptic drugs. Tardive DYSKINESIA is not improved and may be made worse.

There are few signi?cant di?erences between the various antimuscarinic drugs available, but some patients may tolerate one drug better than another or ?nd that they need to adjust their drug regimen in relation to food.... benzhexol

Disopyramide

One of the ANTIARRHYTHMIC DRUGS given by intravenous injection after myocardial infarction to restore supraventricular and ventricular arrhythmias to normal, particularly when patients have not responded to lidocaine (lignocaine). It can impair the contractility of heart muscle and it does have an antimuscarinic e?ect (see ANTIMUSCARINE); consequently its administration has to be undertaken with care, especially in patients with GLAUCOMA or enlargement.... disopyramide

Incontinence

Urinary incontinence The International Continence Society de?nes urinary incontinence as an involuntary loss of URINE that is objectively shown and is a social and hygiene problem. The elderly suffer most from this disorder because the e?ectiveness of the sphincter muscles surrounding the URETHRA declines with age. Men are less often affected than women; 20 per cent of women over 40 years of age have problems with continence. It is estimated that around three million people are regularly incontinent in the UK, a prevalence of about 40 per 1,000 adults.

Incontinence can be divided broadly into two groups: stress incontinence and incontinence due to an overactive URINARY BLADDER – also called detrusor instability – which affects one-third of incontinent women, prevalence increasing with age. Bladder symptoms do not necessarily correlate with the underlying diagnosis, and accurate diagnosis may require urodynamic studies – examination of urine within, and the passage of urine through and from, the urinary tract. However, such studies are best deferred until conservative treatment has failed or when surgery is planned.

Incontinence causes embarassment, inconvenience and distress in women, and men are reluctant to seek advice for what remains a social taboo for most people. Su?erers should be encouraged to seek help early and to discuss their anxieties and problems frankly. Often it is a condition which can be managed e?ectively at primary care centres, and quite simple measures can greatly improve the lives of those affected. STRESS INCONTINENCE is the most common cause of urinary incontinence in women. This is the involuntary loss of urine during activities that raise the intra-abdominal pressure, such as sneezing, coughing, laughing, exercise or lifting. The condition is caused by injury or weakness of the urethral sphincter muscle; this weakness may be either congenital or the result of childbirth, PROLAPSE of the VAGINA, MENOPAUSE or previous surgery. A CYSTOCOELE may be present. Urinary infection may cause incontinence or aggravate the symptoms of existing incontinence.

The ?rst step is to diagnose and treat infection, if present. Patients bene?t from simple advice on incontinence pads and garments, and on ?uid intake. Those with a high ?uid intake should restrict this to a litre a day, especially if frequency is a problem. Constipation should be treated and smoking stopped. The use of DIURETICS should be reduced if possible, or stopped entirely. Postmenopausal women may bene?t from oestrogen-replacement therapy; elderly people with chronic incontinence may need an indwelling urethral catheter.

Pelvic-?oor exercises can be successful and the insertion of vaginal cones can be a useful subsidiary treatment, as can electrical stimulation of the pelvic muscles. If these procedures are unsuccessful, then continence surgery may be necessary. The aim of this is to raise the neck of the bladder, support the mid part of the urethra and increase urethral resistance. Several techniques are available. URGE INCONTINENCE An overactive or unstable bladder results in urge incontinence, also known as detrusor incontinence – the result of uninhibited contractions of the detrusor muscle of the bladder. The bladder contracts (spontaneously or on provocation) during the ?lling phase while the patient attempts to stop passing any urine. Hyperexcitability of the muscle or a disorder of its nerve supply are likely causes. The symptoms include urgency (acute wish to pass urine), frequency and stress incontinence. Diagnosis can be con?rmed with CYSTOMETRY. Bladder training is the ?rst step in treatment, with the aim of reducing the frequency of urination to once every three to four hours. BIOFEEDBACK, using visual, auditory or tactile signals to stop bladder contractions, will assist the bladder training. Drug treatments such as CALCIUM-CHANNEL BLOCKERS, antimuscarinic agents (see ANTIMUSCARINE), TRICYCLIC ANTIDEPRESSANT DRUGS, and oestrogen replacement can be e?ective. Surgery is rarely used and is best reserved for di?cult cases. OVERFLOW INCONTINENCE Chronic urinary retention with consequent over?ow – more common in men than in women. The causes include antispasmodic drugs, continence surgery, obstruction from enlargement and post-prostatectomy problems (in men), PSYCHOSIS, and disease or damage to nerve roots arising from the spinal cord. Urethral dilatation or urethrotomy may be required when obstruction is the cause. Management is intermittent selfcatheterisation or a suprapubic catheter and treatment of any underlying cause.

Faecal incontinence is the inability to control bowel movements and may be due to severe CONSTIPATION, especially in the elderly; to local disease; or to injury or disease of the spinal cord or nervous supply to rectum and anal muscles. Those with the symptom require further investigation.... incontinence

Parkinsonism

Parkinsonism, or paralysis agitans, is a progressive disease of insidious onset usually occurring in the second half of life; it is much more common in men than in women. Degenerative changes in the basal ganglia (see BASAL GANGLION) lead to a de?ciency in the NEUROTRANSMITTER, DOPAMINE – or occasionally in other neurotransmitters – and it is this de?ciency that is responsible for most cases.

The clinical picture is characterised by TREMOR, rigidity and poverty of spontaneous movements. The loss of natural play of expression in the face produces a mask-like expression. Rigidity of the larynx, tongue and lips produces a ?at, expressionless voice. The most common symptom is tremor, often affecting one hand, spreading to the leg on the same side, then to the other limbs. It is more pronounced in resting limbs and is exaggerated by excitement, stopping during sleep. It may interfere with eating and dressing. Limb rigidity leads to an increasing tendency to stoop. The patient has a shu?ing walk with a peculiar running gait.

Treatment Several drugs are used to keep the condition under control. None is curative, all have side-effects, and ?nding the most suitable one for any individual depends largely on understanding cooperation between family doctor and patient. Dopaminergic and antimuscarinic (see ANTIMUSCARINE) drugs are used in treatment. Levodopa, a precursor of dopamine, is a long-used example of the former; it produces spectacular improvement in one-?fth and moderate improvement in two-?fths of patients. Benzhexol hydrochloride is one of several antimuscarinic drugs used in Parkinson’s disease; selegiline is a monoamine-oxidase inhibitor used in severe parkinsonism in conjunction with levodopa to reduce ‘end-of-dose’ deterioration. Adverse effects include HYPOTENSION, nausea and vomiting, confusion, and agitation. Some drugs used to treat other disorders produce Parkinsonian side-effects. Patients seeking further advice and help, together with their relatives, are advised to contact the Parkinson’s Disease Society of the UK.... parkinsonism

Selective Serotonin-reuptake Inhibitors (ssris)

These ANTIDEPRESSANT DRUGS have few antimuscarinic effects (see ANTIMUSCARINE), but do have adverse effects of their own – predominantly gastrointestinal. They are, however, much safer in overdose than the tricyclic antidepressants, which is a major advantage in patients who are potentially suicidal. Examples are citalopram, used to treat panic disorders, as well as depressive illness; FLUOXETINE; and PAROXETINE. (See also MENTAL ILLNESS.)... selective serotonin-reuptake inhibitors (ssris)

Tricyclic Antidepressant Drugs

This group of drugs is one of three main types of drugs used to treat DEPRESSION, and was the ?rst to be introduced (in the 1950s). Tricyclic drugs work by blocking the re-uptake of the neurotransmitters SEROTONIN and NORADRENALINE (see NEUROTRANSMITTER), thus increasing the amount of the neurotransmitters at the nerve cell’s receptors. In people with depression, fewer neurotransmitters than normal are released, resulting in a slowing of neural activities. The drugs have a sedative e?ect, which can be useful for depressives with sleep problems, and an antimuscarinic action which can cause dry mouth and constipation (see ANTIMUSCARINE). Overdosage can produce COMA, ?ts (see SEIZURE) and irregular heart rhythm (ARRHYTHMIA). They are sometimes used for treating bed-wetting. (See also ANTIDEPRESSANT DRUGS.)... tricyclic antidepressant drugs



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