The P-I-E-N-O Parkinsn's List Drug Database
bethanechol / UrecholineTM , DuvoidTM
PROMOTILITY:
muscarinic stimulant
Description: Bethanechol is a synthetic parasympathomimetic. It is an old drug originally used to treat urinary retention and stimulate GI motility. However, the availability of metoclopramide and cisapride, and new research on the GI effects of erythromycin, have significantly curtailed the use of bethanechol as a GI stimulant. Bethanechol occasionally is used to offset some of the bothersome anticholinergic reactions to tricyclic antidepressants. Because bethanechol has negligible cardiovascular effects, it is an ideal parasympathomimetic. Bethanechol was approved by the FDA in 1948.
Mechanism of Action: Bethanechol is a synthetic muscarinic stimulant. It does not inactivate acetylcholinesterase. Bethanechol exerts its parasympathomimetic effects by a direct action on muscarinic (cholinergic) receptors, all of which can be antagonized by atropine. Bethanechol primarily affects the urinary and GI tracts. Its effect on the bladder results from stimulation of muscarinic receptors in the detrusor muscle. The detrusor contracts, decreasing bladder capacity and producing urination. Bethanechol also stimulates ureteral peristalsis and relaxes the trigone and external sphincter. Because bethanechol is a direct-acting agonist, spinal cord injury will not compromise these actions.
Stimulation of muscarinic receptors in the GI tract restores peristalsis, increases motility, and increases the resting lower esophageal sphincter pressure. Bethanechol also stimulates the lower GI tract, producing defecation. Bethanechol produces a much more vigorous response in denervated than in normal smooth muscle. It does not stimulate nicotinic receptors and is not degraded by acetylcholinesterase. Bethanechol is a preferred drug in the treatment of postpartum and postoperative nonobstructive urinary retention, and it also can counteract bladder dysfunction often seen with phenothiazines and tricyclic antidepressants.
Pharmacokinetics: Bethanechol is poorly absorbed from the GI tract. Its oral bioavailability is unknown. Parenteral doses are much more potent than equivalent oral doses and should be administered cautiously. Onset of action occurs within 30-90 minutes when taken orally and within 5-15 minutes when given subcutaneously. Distribution of bethanechol is not well known. Due to its quaternary (i.e., charged) state, bethanechol does not penetrate the blood-brain barrier at therapeutic doses. Because it is not susceptible to degradation by acetylcholinesterase, bethanechol has a longer duration of action than endogenous acetylcholine. Nevertheless, it is a short-acting drug; effects typically last 1 hour when taken orally and 2 hours when taken subcutaneously. The mechanism of elimination is unknown.
CONTRAINDICATIONS/PRECAUTIONS: Bethanechol is absolutely contraindicated when the strength or integrity of the bladder wall is in question, as in the surgical bladder. As with urinary tract obstruction, GI obstruction, inflammatory bowel disease, and peptic ulcer disease, increased muscular contraction increases the risk for rupture or perforation and worsening of the underlying condition. Similarly, any post-GI surgery patient must be treated carefully.
Bethanechol will stimulate gastric acid secretion and is therefore contraindicated in peptic ulcer disease.
Because it can cause a mild negative chronotropic effect, bethanechol is contraindicated in patients with bradycardia, coronary artery disease, atrioventricular conduction defects, or any cardiac disease in which decreasing the heart rate poses a risk for decreasing cardiac or peripheral perfusion.
Bethanechol should not be used in asthma or COPD patients because cholinergic stimulation constricts the airways.
Bethanechol is also contraindicated in patients with hyperthyroidism, seizures, and parkinsonism because it can exacerbate these conditions.
Bethanechol is classified as a pregnancy category C drug. Because adequate studies have not been done, it is unknown whether bethanechol is teratogenic.
DRUG INTERACTIONS: Bethanechol's cholinergic effects are additive when used in combination with other parasympathomimetics, whether direct cholinergic agonists or anticholinesterases; this can lead to a severe cholinergic reaction.
Bethanechol and atropine are pharmacological opposites; each is antagonized by the other. These two agents should not be used together.
Bethanechol offsets the effects of epinephrine and other sympathomimetics at sites where sympathomimetic and cholinergic receptors have opposite effects.
Procainamide and quinidine have been shown to counteract bethanechol's cholinergic effect on muscle.
Bethanechol has been used to counteract the bothersome, anticholinergic side effects of tricyclic antidepressants. In general, this pharmacodynamic interaction is not harmful; bethanechol does not interfere with the therapeutic action of the antidepressant, nor does it enhance its cardiovascular toxicity.
ADVERSE REACTIONS: Bethanechol can produce abdominal pain and discomfort, diarrhea, nausea/vomiting, and borborygmi. These reactions result from increased tone and peristaltic activity in the stomach and intestines.
Flushing and warmth of the skin, particularly about the face; diaphoresis; lacrimation; and salivation are effects on the skin and glands that are mediated by acetylcholine, and thus are side effects of bethanechol.
Cholinergic agonists have the potential to cause bronchospasm. Bethanechol should be used cautiously in patients with asthma.
Miosis is a frequent and classic side effect of cholinergic stimulation. In general, this effect is not harmful.
Urinary urgency is an expected result of the treatment for retention.
Other reported side effects include hypothermia, retrograde urine flow sometimes leading to infection, and a mild blood pressure decrease with reflex tachycardia. A more precipitous drop in blood pressure can be seen in hypertensive patients.
Parenteral use of bethanechol can result in a severe cholinergic reaction, possibly causing vascular collapse, shock, and cardiac arrest.
PATIENT INFORMATION:
What do bethanechol tablets do?
Bethanechol (UrecholineTM , DuvoidTM ) stimulates the bladder. It can help people who are having trouble passing urine to empty their bladder. Generic bethanechol tablets are available.
What should my doctor, dentist, or pharmacist know before I take bethanechol?
They need to know if you have any of these conditions:
How should I take this medicine?
Take bethanechol tablets by mouth. Follow the directions on the prescription label. Swallow the tablets with a drink of water. It is best to take bethanechol on an empty stomach, 1 hour before or 2 hours after meals. Take your doses at regular intervals. Do not take your medicine more often than directed. Do not stop taking except on your doctor's advice.
Special precautions for use in children:
Safe use in children has not been established.
What if I miss a dose?
If you miss a dose, take it as soon as you can. If it is almost time for your next dose, take only that dose. Do not take double or extra doses.
What other medicines can interact with bethanechol?
Tell your doctor or pharmacist: about all other medicines you are taking, including non-prescription medicines; if you are a frequent user of drinks with caffeine or alcohol; if you smoke; or if you use illegal drugs. These may affect the way your medicine works. Check before stopping or starting any of your medicines.
What side effects may I notice from taking bethanechol?
Serious side effects with bethanechol include:
Call your doctor as soon as you can if you get any of these side effects.
Minor side effects with bethanechol include:
Let your doctor know about these side effects if they do not go away or if they annoy you.
What do I need to watch for while I take bethanechol?
Visit your doctor for regular checks on your progress.
You may get dizzy or lightheaded. Do not drive, use machinery, or do anything that needs mental alertness until you know how methysergide affects you. To reduce the risk of fainting spells, do not stand or sit up quickly, especially if you are an older patient.
Where can I keep my medicine?
Keep out of the reach of children in a container that small children cannot open.
Store at room temperature below 40C (104F). Keep container tightly closed. Throw away any unused medicine after the expiration date.
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