NURS488 GI meds

Anticholinergics

Antiemetic

MoA: bind to and block AcH receptors in inner ear labrynth

AE: dry mouth, dry eyes, constipation

Interactions: additive effects w antidepressants and antihistamines

Histamine drugs (H1 receptor blockers)

Antiemetic

MoA: inhibit AcH by binding to H1 receptors → prevents cholinergic stimulation in vestibular & reticular areas

AE: dizziness, drowsiness, blurred vision, dry mouth

Interactions: increased CNS depression w barbiturates, opioids, hypnotics, tricyclic antidepressants, and alcohol

Seratonin blockers

Antiemetic

MoA: blocks seratonin receptors in GI tract, CTZ, and VC

AE: headache, constipation

Tetrahydrocannabinoids

Antiemetic

MoA: inhibitory effects on reticular formation, thalamus, and cerebral cortex. alters mood and body perception of its surroundings

AE: drowsiness, dry mouth, dizziness

Neuroleptic drugs

Antiemetic

MoA: blocks dopamine receptors on CTZ

AE: sedative effects, EPS, anticholinergic effects, orthostatic hypotension

Prokinetic drugs

Antiemetic

MoA: blocks dopamine in CTZ, desensitizes CTZ, and stimulates peristalsis to promote gastric emptying

AE: abdominal cramps, diarrhea, EPS

Apreprend/ NK1 antagonist

Antiemetic

MoA: selective agonist at substance P/NK1

AE: dizziness, headache, insomnia, GI upset

Antimotility - opiates

Antidiarrheal

MoA: ↓bowel motility, relieve rectal spasms, ↑transit time through bowel for ↑ water and electrolyte absorption

AE: drowsiness, sedation, lethargy, anorexia, N/V, constipation, resp depression, ↓HR, ↓BP, urinary retention, flushing, rash, urticaria

Lomotil

Antidiarrheal

Diphenoxylate w atropine; subtherapeutic amounts of atropine discourages recreational use of diphenoxylate b/c high doses result in extreme anticholinergic effects.

Absorbents

Antidiarrheal

MoA: coat the walls of the GI tract and binds to causative agent and promotes excretion

AE: increased bleeding time, constipation, confusion, twitching, hearing loss, tinnitus, blue gums

Interactions: decrease absorption of many drugs, careful with anticoagulants

Antimotility (anticholinergics)

Antidiarrheal

MoA: ↓intestinal muscle tone and peristalsis, so slows movement

AE: urinary retention/hesitance, impotense, headache, confusion, dizziness, anxiety, drowsiness, dry skin, rash, flushing, blurred vision, photophobia, increased intraoccular pressure, ↑↓BP, ↑↓HR

Intestinal flora modifiers

Antidiarrheal

MoA: supplies missing bacteria to GI tract, suppressing growth of diarrhea causing bacteria

Misoprostol

Acid controlling

Cytoprotective: ↑ local production of mucous and bicarbonate, promotes local cell regeneration, maintains mucosal blood flow

Indication: prevention of NSAID induced ulcers

Sucralfate

Acid controlling

Cytoprotective: binds to the base of ulcers, forming a protective layer

Indication: stress ulcers, PUD

AE: constipation, dry mouth, nausea

Nursing consideration: give >2h after other drugs

Histamine 2 (H2) antagonists

Acid controlling

MoA: blocks H2 receptors, decreases acid production and secretion

Indications: GERD, erosive esophagitis, PUD, upper GI bleed

AE: impotence, gynecomastia, headache, lethargy, confusion, diarrhea, urticaria, sweating, flushing

Interactions: changes absorption of some drugs

Proton pump inhibitors

Acid controlling

MoA: binds to hydrogen, prevents movement of hydrogen into stomach, so all secretion temp blocked

Indications: GERD, erosive esophagitis, duodenal and gastric ulcers, Zollinger-Ellison syndrome, H-pylori induced ulcers

Interactions: ↑ risk of bleeding w warfarin, ↓serum levels of diazepam and phenytoin

Nursing considerations: works best if 30-50 mins before eating

Antacids

Acid controlling

MoA: neutralizes stomach acid, promotes secretion of bicarb, prostaglandin, and mucous

Contraindications: severe kidney failure, electrolyte disturbances, GI obstruction

AE: constipation (aluminum), diarrhea (magnesium), gas and belching (calcium)

Hyperosmotic laxatives

MoA: ↑fecal water content which distends bowel, stimulating peristalsis

AE: abdominal bloating, rectal irritation, electrolyte imbalance

Stimulant laxatives

MoA: ↑peristalsis via intestinal nerve stimulation

AE: nutrient malabsorption, skin rash, rectal irritation, gastric irritation, electrolyte imbalance

Saline laxatives

MoA: ↑osmotic pressure, ↑water in intestines → bowel distension and peristalsis

AE: magnesium toxicity, thirst, cramping, diarrhea, electrolyte imbalance

Bulk forming laxatives

MoA: high fiber → absorb water to increase bulk, distends bowel

AE: impaction, fluid overload, electrolyte imbalance, esophageal blockage

Emollient laxatives

MoA: promotes more water and fat in the stool (softens and lubricates

AE: skin rash, decreased vitamin absorption, electrolyte imbalance