Exam 2 Flashcards
Where are muscarinic receptors located?
Heart muscle, sphincters of bladder and gi tract, bronchioles of lungs, sweat glands, iris constrictor
Name the prototype drug that represents the muscarinic agonists. This drug works by reversibly binding directly to and activating muscarinic receptors. It has no effect on nicotinic receptors.
Bethanechol (Urechol)
What 4 areas does bethanechol effect that can cause adverse reactions?
heart, exocrine glands, smooth muscle, and eye
There are three therapeutic uses for bethanechol, one approved one and two invesitgational or off label ones, what are they?
treating urinary retention postoperatively is the approved one, it is also used investigationally for treating GERD and GI paralysis.
Name some of the adverse effects of bethanechol.
cardiovascular effects such as hypotension and bradycardia, alimentary effects such as increased salivation, secretions, diarrhea and involuntary defecation, bronchoconstriction, dysrhythmia in hyperthyroid patients.
Name three sources of toxicology due to muscarinic agonists.
ingestion of inocybe an clitocybe mushrooms, overdose on direct acting musarinic agonists such as bethanechol and pilocarpine, and overdose on cholinesterase inhibitors
What is the treatment for overdose on muscarinic agonists?
atropine - a muscarinic blocking agent
Name the prototype muscarinic antagonist which competitively blocks Acetylcholine action. It can be extracted from plants.
Atropine
Name the seven things that atropine does.
increases heart rate, decreases secretions, relaxes bronchi, decreases bladder tone, decreases GI motility and tone, dilates the pupil and relaxes the ciliary muscle, CNS excitation.
From low to high doses, what areas and in what order does atropine effect?
secretions, heart, eye, urinary tract, intestine, lung, stomach
Name some therapeutic uses for atropine.
preanesthesia to block the baroreceptor reflex and keep heart rate from dropping, eye disorders and exams to cause mydriasis (pupil enlargement) and paralysis of ciliary muscle, bradycardia, intestinal hypertonicity and hypermotility, muscarinic agonist poisoning, peptic ulcer disease, asthma, gall stones (relaxes biliary tract smooth muscle)
Name some adverse effects of atropine.
xerostomia (dry mouth), blurred vision, elevated intraocular pressure, urinary retention, constipation, anhidrosis (low or absent sweat), tachycardia, thickening and drying of bronchial secretions.
What are some sources of antimuscarinic poisoning?
natural products like atropa belladonna and datura stramonium, overdose of atropine or scopolamine, other drugs with pronounced antimuscarinic properties like antihistamines, phenothiazines, antipsychotics, and tricyclic antidepressants.
What are some drugs that atropine interacts with?
any drug that causes muscarinic block - antihistamines, phenothiazine, antipsychotics, tricyclic antidepressants.
What is the treatment for toxicology to muscarinic antagonists?
physostigmine which is a cholinesterase inhibitor, syrup of ipecac and activated charcoal can also be used.
Urinary frequency, urgency, nocturia, and urge incontinence are all symptoms of what pathology?
overactive bladder (OAB)
What class of drugs is used to treat overactive bladder and what is the mechanism of action?
Anticholinergic drugs are used, they work by blocking muscarinic receptors on the bladder detrusor muscle and inhibit bladder contractions and voiding. They block specific M3 receptors (bladder, GI, eye, and salivary glands)
Name some of the anticholinergic drugs used to treat OAB.
oxybutynin (ditropan, oxytrol), darifenacin/enablex (highly M3 selective), solifenacin/vesicare (primarily M3 selective), tolterodone/detrol (nonselective), trospium (sanctura)
Cholinesterase inhibitors are used to treat what condition?
myasthenia gravis
What are the two basic categories of cholinesterase inhibitors?
reversible and irreversible
Name the prototype reversible cholinesterase inhibitor and discuss its mechanism of action.
Neostigmine. It intensifies neurotransmitters action and causes muscarinic responses similar to muscarinic agonists. At the neuromuscular junction it causes increased force of contraction and at toxic levels can cause constant depolarization. Can cause some mild CNS stimulation and CNS depression can result with toxic levels.
Name two therapeutic uses for neostigmine.
myasthenia gravis and reversal of nondepolarizing neuromuscular blockade. (postoperative or OD on muscle relaxant)
What are some adverse reactions of neostigmine?
excessive muscarinic stimulation, neuromuscular blockade - too much Ach at the receptor leads to constant stimulation and paralysis.
Name the only irreversible cholinesterase inhibitor that is used medicinally and what condition is it used to treat?
echothiophate and it is used for glaucoma. It’s pharmacologic effects are exactly like the reversible cholinesterase inhibitors but produces a state of cholinergic crisis.
Name the only irreversible cholinesterase inhibitor that is used medicinally and what condition is it used to treat?
echothiophate and it is used for glaucoma
What is cholinergic crisis?
It is caused by overdose on a cholinesterase inhibitor and results in muscle weakness and paralysis due to constant Ach stimulation. There is excessive muscarinic stimulation and medical treatment such as atropine and respiratory support is needed.
How can you differentiate between myasthenia crisis and cholinergic crisis?
A challenge dose of an ultrashort acting cholinesterase inhibitor (edrophonium) can be given, if symptoms improve then it is a myasthenia crisis, it they worse it is a cholinergic crisis.
How can you differentiate between myasthenia crisis and cholinergic crisis?
A challenge dose of an ultrashort acting cholinesterase inhibitor (edrophonium) can be given, if symptoms improve then it is a myasthenia crisis, it they worse it is a cholinergic crisis.
What are the 4 cholinesterase inhibitors used to treat alzheimer’s disease?
doneprazil, galantamine, rivastigamine, tacrine
What are the 4 cholinesterase inhibitors used to treat alzheimer’s disease?
doneprazil, galantamine, rivastigamine, tacrine
What is the different between polarizing and depolarizing nicotinic blocking agents?
Depolarizing agents don’t let the depolarization and repolarization process happen. The muscle contracts and then relaxes. Nonpolarizing agents compete with ACh and bind to NicotinicM receptors and block ACh action.
What is the prototype drug that is given for nondepolarizing neuromuscular blockers and what is its mechanism of action?
Tubocurarine is the drug and it works by competing with ACh at the neuromuscular junction and not activating the receptor. It works like an antagonist.
What are the therapeutic uses of tubocurarine and similiar acting drugs?
muscle relaxation for surgery mechanical ventilation and other diagnostic procedures, as well as the diagnosis of myasthenia gravis.
What are the therapeutic uses of tubocurarine and similiar acting drugs?
muscle relaxation for surgery mechanical ventilation and other diagnostic procedures, as well as the diagnosis of myasthenia gravis.
What are some adverse effects of tubocurarine?
respiratory arrest due to respiratory muscle relaxation and cardiovascular effects such as hypotension, bradycardia, dysrhythmias, and cardiac failure due to sympathetic blockade, histamine release and other unknown mechanisms.
What is the prototype drug for depolarizing neuromuscular blcokers and what is its mechanism of action?
succinyl choline and it is structurally similar to acetylcholine and causes depolarization of them muscles followed by a depolarizing blockade. Thus there is muscle contraction followed by relaxation.
What is the prototype drug for depolarizing neuromuscular blcokers and what is its mechanism of action?
succinyl choline and it is structurally similar to acetylcholine and causes depolarization of them muscles followed by a depolarizing blockade. Thus there is muscle contraction followed by relaxation.
What are the pharmacologic effects of succinyl choline?
muscle relaxation, contraction before paralysis which is ultrashort, muscle cramps following administration due to initial contraction, no effect on the CNS.
What are some adverse effects of succinyl choline?
the most unique one is malignant hyperthermia characterized by muscle rigidity and high temperatures and is genetically determine. Others include prolonged apnea in people with low pseudocholinesterase activity, postoperative muscle pain due to contraction, hyperkalemia can occur because the drug promotes release of potassium from tissues and so is contraindicate din burn victims.
What are the problems with and treatment options for succinyl choline toxicity?
Toxicity causes prolonged apnea with no antidote, treatment is purely support based.
What are the problems with and treatment options for succinyl choline toxicity?
Toxicity causes prolonged apnea with no antidote, treatment is purely support based.
How long do long-acting nondepolarizing agents work and what are three such agents?
They last 25-100 minutes and three of these drugs would be doxacurium, metocurine, pipecuronium.
How long do short-acting nondepolarizing agents work and what is one such agent?
They last 10-15 minutes and the medication is mivacurium.
Name two ganglionic blockers and discuss their mechanism of action.
The two drugs are trimetaphan and mecamylamine (inversine). They work by competing with ACh at nictotinicN receptors in the autonomic ganglia. This occurs nondiscriminately and can affect both sympathetic and parasympathetic ganglia.
Name two ganglionic blockers and discuss their mechanism of action.
The two drugs are trimetaphan and mecamylamine (inversine). They work by competing with ACh at nictotinicN receptors in the autonomic ganglia. This occurs nondiscriminately and can affect both sympathetic and parasympathetic ganglia.
What are the adverse effects of ganglionic blockers?
antimuscarinic effects such as parasympathetic blockade, hypotension due to sympathetic blockade, CNS effects since it crosses the BBB -tremor and convulsions.
What are the adverse effects of ganglionic blockers?
antimuscarinic effects such as parasympathetic blockade, hypotension due to sympathetic blockade, CNS effects since it crosses the BBB -tremor and convulsions.
