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pharm test 3
Pharm cholinergic agents ch. 19
Question | Answer |
---|---|
cholinergic agents **cholinergic agonists; parasympathomimetics | drugs that stimulate the parasympathetic nervous system (PSNS) **rest and digest **NT: acetylcholine (ACh) |
cholinergic receptors | -nicotinic and muscarinic **muscarinic: most responsible for having beneficial affects we are looking for in these drugs **nicotinic: causes more of the S/E we dont like to see |
nicotinic receptors | -located in the ganglia of both the PSNS and SNS -named "nicotinic" b/c it can be stimulated by the alkaloid nicotine |
muscarinic receptors | -located postsynaptically: smooth muscle, cardiac muscle, glands of the parasympathetic fibers, effector organs of cholinergic sympathetic fibers |
indirect acting cholinergic agonists | -inhibit the enzyme cholinesterase, which breaks down ACh; result is more ACh available at the receptors **anticholinesterase means youre making more ACh available for you to have a cholinergic response |
DRUG EFFECTS of PNS SLUDGE **cholinergic makes you have lots of fluids (difficulty breathing); eyes running, nose running, hard to breathe | -Salivation -Lacrimation -Urinary incontinence -Diarrhea -Gastrointestinal cramps -Emesis |
DRUG EFFECTS of cholinergic | -stimulate intestine & bladder: increased gastric secretions, increased gastrointestinal motility, increased urinary frequency -stimulate pupil: constriction (miosis), reduced intraocular pressure -increased salivation & sweating |
DRUG EFFECTS of cholinergic | -CV effects: decreased HR, vasodilation -respiratory effects: bronchial constriction, narrowed airways |
DRUG EFFECTS of cholinergic | -at recommended doses, the cholinergics primarily affect the muscarinic receptors -at high doses, cholinergics stimulate the nicotinic receptors |
DRUG EFFECTS of cholinergic | -desired effects: from muscarinic receptor stimulation -many undesirable effects are d/t stimulation of the nicotinic receptors |
INDICATIONS: direct-acting agents | -reduce intraocular pressure -useful for glaucoma & intraocular surgery (ACh, carbachol, pilocarpine) |
INDICATIONS: direct-acting agents: bethanechol | -increases tone & motility of bladder & GI tract -relaxes sphincters in bladder & GI tract, allowing them to empty |
INDICATIONS: indirect-acting agents | -cause skeletal muscle contractions -used for diagnosis & treatment of myasthenia gravis -used to reverse anticholinergic poisoning (antidote) ex: physostigmine, pyridostigmine |
INDICATIONS: indirect-acting agents: donepezil (aricept) | -used in treatment of mild to moderate alzheimer's disease -helps to increase or maintain memory & learning capabilities **helps to a certain point, does not last forever or cure it |
side effects **a result of overstimulation of the PSNS | CV: bradycardia, hypotension, conduction abnormalities (AV block & cardiac arrest) CNS: headache, dizziness, convulsions GI: abdominal cramps, increased secretions, nausea, vomiting RESP: increased bronchial secretions, bronchospasms |
Interactions | -anticholinergics, antihistamines, sympathomimetics: antagonize cholinergic agents, resulting in decreased responses -other cholinergic agents: additive effects |
NURSING IMPLICATIONS | -encourage patients with myasthenia gravis to take medication 20 min b4 eating to help improve chewing & swallowing -therapeutic effects of donepezil may not occur for up to 6 weeks |
NURSING IMPLICATIONS | **atropine is the antidote for cholinergics |
Monitor for therapeutic effects | -alleviated S/S of myasthenia gravis -in post-op pt. with decreased GI peristalsis, look for: increased bowel sounds, passage of flatus, occurrence of bowel movements |
Monitor for therapeutic effects | -in pt. w/ urinary retention/hypotonic bladder, urination should occur w/in 60 min of bethanechol administration |
a patient is taking the direct acting cholinergic drug bethanechol (urecholine) before meals. after 3 days, he calls his health care provider's office & complains of occasional nausea & vomiting. the nurse should give which instruction? | take this medication with meals to reduce GI upset |
the family of a patient who has recently been diagnosed with alzheimer's disease is asking about the new drug perscribed to treat this disease. the patients wife says shes excited for him to start. what should the nurse reply | "these drugs dont cure alzheimers disease. lets talk about what the physician said to expect with this drug therapy" |
the nurse is giving a dose of bethanechol to post-op pt. the nurse is aware that contraindications to bethanechol include: | peptic ulcer |
a patient took an accidental overdose of a cholinergic drug while at home. he comes to ER w/ severe abd, cramping & bloody diarrhea. the nurse expects which drug will be used to treat this pt? | atropine |
a pt. w/ myasthenia gravis has received a perscription for pyridostigmine. the nurse should include which teaching point for this pt? | the drug should be taken 30 min before eating meals |
when giving IV cholinergic drugs, the nurse must watch for symptoms of a cholinergic crisis, such as: | -hypotension -syncope -dyspnea |