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pharm test 3
Pharm cholinergic-blocking agents ch. 20
Question | Answer |
---|---|
cholinergic blocking agents | drugs that block or inhibit the actions of ACh in the parasympathetic nervous system |
mechanism of action | -competitive antagonists -compete with ACh -block ACh at the muscarininc receptors in the PSNS, as a result ACh is unable to bind to the receptor site & cause a cholinergic effect |
Chemical Class | -atropine -belladonna -hyoscyamine -scopolamine |
atropine | used to dry up before surgery (dry secretions); also used to make the heart speed up |
belladonna | usually used for motion sickness |
hyoscyamine and scopolamine | used for GI |
DRUG EFFECTS | CV: small doses--decrease HR; large doses-- increase HR CNS: small doses-- decrease muscle rigidity & tremors; large doses-- drowsiness, disorientation, hallucinations |
DRUG EFFECTS | EYE: dilated pupils (mydriasis); decreased accomodation d/t paralysis of ciliary muscles (cycloplegia) GI: relax smooth muscle tone, decrease intestinal & gastric secretions, decrease motility & peristalsis |
DRUG EFFECTS | GENITOURINARY: relaxed detrusor muscle, increased constriction of internal sphincter--urinary retention as a result GLANDULAR: decreased bronchial secretions, salivation, & sweating RESP: decreased bronchial secretions, dilated bronchial airways |
side effects | -blind as a bat -red as a beet -bloated as a toad -mad as a hatter -hot al hell |
INDICATIONS: CNS | -decreased muscle rigidity & muscle tremors -Parkinson's disease -drug induced extrapyramidal reactions |
INDICATIONS: CV | they affect the heart's conduction system -at low doses: slows the HR -high doses: increase HR |
INDICATIONS: atropine | used primarily for CV disorders -sinus node dysfuntion -sinus bradycardia w/ hemodynamic compromise -sympathetic 2nd degree heart block |
INDICATIONS: RESPIRATORY | blocking cholinergic stimulation of the PSNS allows unopposed action of the SNS, results: -decreased secretions from nose, mouth, pharynx, & bronchi -relaxed smooth muscle in bronchi & bronchioles -decreased airway resistance -bronchodilation |
INDICATIONS: RESPIRATORY | respiratory agents are used to treat: -exercise induced bronchospasms -chronic bronchitis -asthma -chronic obstructive pulmonary disease |
INDICATIONS: GI | PSNS controls gastric secretions & smooth muscles that produce gastric motility; blockade of PSNS results in: -decreased secretions -relaxation of smooth muscle -decreased GI motility & peristalsis |
INDICATIONS: GI | GI agents are used to treat: -peptic ulcer disease -irritable bowel syndrome -GI hypersecretory states |
INDICATIONS: GENITOURINARY | -relaxed detrusor muscles of the bladder -increased constriction of the internal sphincter -reflex neurogenic bladder -incontinence |
other anticholinergics | glycopyrrolate (robinul): control secretions, especiall pre-op; just liek atropine in that it dries up secretions pre-op |
Interactions | -antihistamines, phenothiazines, tricyclic antidepressants, MAOIs -when given with cholinergic blocking agents, cause additive cholinergic effects, resulting in increased effects |
Nursing Implications | if pt. has GI or GU obstruction you do not want to use anticholinergics |
If you have glaucoma should you take anticholinergics? | NO; DO NOT TAKE IF YOU HAVE GLAUCOMA |
nursing implication | dry mouth may occur; can be handled by chewing gum, frequent mouth care, and hard candy |
what is the antidote for atropine overdose? | physostigmine |
monitor for side effects | -constipation -tremors -hallucinations -urinary retention -fever -tachycardia -confusion -sedation -hot, dry skin -CNS depression: occurs with large doses of atropine |
the nurse is providing education about anticholinergic drug therapy to an elderly pt. an important point to emphasize would be to | avoid exposure to high temperatures |
when giving anticholinergic drugs, the nurse keeps in mind that contraindications include | benign prostatic hyperplasia |
when assessing for adverse effects of anticholinergic drug therapy, the nurse would expect to find that the patient complains of which effect? | dry mouth |
the nurse administering a cholinergic-blocking drug to a patient who is experiencing drug-induced extrapyramidal effects would assess for which therapeutic effect? | decreased muscle rigidity |
during assessment of pt. about to receive a cholinergic blocking drug, the nurse should determine whether the pt. is taking any drugs that may potentially interact with the anticholinergic | tricyclic antidepressants |
a pt. has been given a perscription for transdermal scopolamine patches for motion sickness for use during a vacation cruise. the nurse will include which instructions? | -apply patch 3-4 hrs. before boarding the ship -patch should be placed on a nonhairy area just behind your ear -change patch every 3 days -rotate the application sites |