chapter 52 pharm 343 Flashcards
*meclizine (antivert)
treat dizziness, vertigo, and N&V associated with motion sickness. shock and lactation is contraindicated. oral use only.
*metoclopramide (reglan)
only in prescription form. treatment of delayed gastric emptying and gastroesophageal reflux and also an antiemetic. contraindicated with pts with seizures, pheochromocytoma, breast cancer, GI obstruction. oral and parenteral forms. developing tardive dyskinesia-facial disfiguration. with long term use of drug.
*ondansetron (zofran)
prototypical drug. breakthru in chemo and postoperative. treatment of vomiting and nausea in pregnancy. oral and injectable forms.
*prochlorperazine (compazine)
most commonly used. these drugs have antidop, antihist, and anticholinergic properties. concerns over QT widening and ventricular dysrhythmias. injectable form used. contraindicated in pts with hypersensitivity to phenothiazines, those in coma, seizures, encephalopathy, or bone marrow suppression. oral and injectable forms.
Antiemetic drugs
drugs given to relieve nausea and vomiting. when drugs from different categories are combined, the antiemetic effectiveness is increased because more than one pathway becomes blocked. minimizing or preventing fluid and electrolyte disturbancesand minimize detterioration of the pts nutrition. most work by blocking CNS but some work with GI.
chemoreceptor trigger zone (CTZ)
the area of the brain that is involved in the sensation of nausea and the action of vomiting. neurotransmitters are sent from the CTZ which alert the brain of the nausea signs. Once stimulated, it triggers vomiting effect.
vomiting center
the area of the brain that is involved in stimulating the physiologic events that lead to nausea and vomiting.
types of nausea and vomiting
chemotherapy-induced and postoperative.
emesis
the forcible emptying or expulsion of gastric and intestinal contents through the mouth also called vomiting.
mechanism of antiemetics anticholinergic
most work by blocking vomiting pathways. they block the neurologic stimulus that induces vomiting. anticholinergic drugs as antiemetics, they act by binding to and blocking ACh recepters in the vestibular nuclei which located deep in brain. when ACh is prevented from binding, nausea signals cant be transmitted. anticholinergics tend to dry GI secretions and reduce smooth muscle spasms.
nausea
sensation often leading to the urge to vomit.
mechanism of antihistamines emetics
work similar to anticholinergics. antisecretory and antispasmodic effects. antihistamines prevent cholinergic stimulation in vestibular and reticular systems. nausea and vomiting occur when these vsystems are stimulated.
mechanism of antipaminergic emetics
antipsychotic effects and nausea and vomiting by blocking dopamine receptors in the CTZ. also anticholinergic actions. calm CNS.
maechanism of prokinetic emetic
work as antiemetics by blocking dopamine receptors in CTZ which decreases sensitivity of CTZ with GI tract. action is to stimulate peristalsis in GI.
mechanism of serotonin blockers enemetic
work by blocking serotonin receptors located in GI, CTZ, and vomiting centers. subtypes-CNS, smooth muscle, platelets, and GI tract. subtype used is (5-HT3) receptor.
mechanism of tetrahydrocannabinol emetic
substance in marijuana. dronabinol used as an antiemetic bcuz of the drugs inhibitory effects on the reticular formation, thalamus, and cerebral cortex.
adverse effects for antiemetic drugs
is blockade of various receptors.
interactions antiemetic drugs
anticholinergic drugs have drying effects with antihistamines and antidepressants. increased CNS depressant with antihistamine antiemetics with barbs, opiods, hypnotics, tricyclic antidepressants, and alcohol. increase CNS depressants with alcohol and antidopaminergic.
anticholinergic drugs
contraindicated with pts with glaucoma. transdermal patch more common.
prokinetic emetic
promote ovement thru the GI tract and increase GI motility.
serotonin blockers emetic
also called 5-HT3 bcuz they block the 5HT3 receptors in the GI tract, CTZ, and vomit center. very few adverse events. prevention of nausea and vomiting with cancer chemotherapy. a dose is usually given 30mins before the end of the surgery. drug given in the first 24-48 hrs of chemo. pregnancy category B drugs. risk of cardiac dysrhythmias.
tetrahydrocannabinol emetic
stimulate appetite and weight gain.
