Pharmacology 2 Flashcards
(35 cards)
What consitutes a dx of constipation?
< 3 Bowel movements per week
Describe the Rome III criteria of constipation.
> 25% of the time you have:
- straining
- lumpy/hard stool
- incomplete evacuation
- sensation of anorectal blockage
- manual maneuvers needed
Plus less than 3 BMs a week.
Study used to diagnose constipation?
Sitz marker study: measures number of markers passed in a 24hr period
Anorectal manometry (balloon expulsion test):
Defecography: evaluates anorectal function via barium insertion into the rectum
How many grams of fiber recommended per day?
~25 grams per day
Most commonly used laxatives for colonoscopy prep?
Osmotic laxatives (MgOh, Mgcitrates, Polyethelene glycol, lactulose
What is the indication for Linaclotide (Lizness)
- Chronic idiopathic constipation.
- IBS- constipation as well.
Increases Cl and HCO3 secretions through CFTR ion channel via cGMP increase
Adverse effects of Linaclotide (Lizness)
Diarrhea, abdominal pain, flatulence
Contraindications of Linaclotide (Lizness)?
Mechanical GI obstructions
Peds <6 y/o
Pregnancy category C
What drug is used to counteract Opioid-induced constipation?
Methylnaltrexone (Relistor)
Selective PERIPHERAL opioid receptor antagonist
Adverse effects of Methylnaltrexone (Relistor)?
Abdominal pain Flatulence Nausea Dizziness Hyperhidrosis Bowel Perforation (rare)
Contraindications of Methylnaltrexone (Relistor)?
mechanical GI obstruction
pregnancy B
Definition of diarrhea?
increase in daily stool weight above 200 grams, liquidity
must be diff. from “loose Bowel Movement”
Most useful in clinical practice for eval/treatment of patients with diarrhea?
History and stool characteristics
Drug indicated for diarrhea secondary to hypercholesterolemia?
Bile acid sequestrants (colesevalam powder)
also off label for bile acid diarrhea due to distal ileum resection and C. difficile diarrhea.
Adverse effects of bile acid sequestrants?
Nausea, vomiting, abdomen pain, heartburn, bloating.
Acidosis 2nd to hyperchloremia, gallstones, pancreatitis, peptic ulcers, malabsorption, Vit. K deff assoc. coagulopathy.
Where is the central vomiting center in the brain?
What projects to it?
Medulla
- Lateral Reticular Formation
- Chemoreceptor Trigger Zone (CTZ) (bottom of 4th ventricle)
- GI —> Vagus Nerve
- Cortex (anticipatory)
- Vestibular apparatus (motion sickness)
Describe the vomiting center outputs and the receptors acted on by the medulla?
Outputs are CN 5/7/9/10/12
Act on: Muscarinic cholinergics (AChm), Histamine type 2 (H2), Serotonin type 2 (5HT2)
Describe a drug mainly used as motion sickness prophylaxis?
Contraindications?
Scoploamine (patch form) - antimuscarinic action
M1 receptor antagonist - blocks vestibular inputs to central vomiting center
CNS depression, dry mouth, Restlessness/irritability.
DONT TAKE if have Glaucoma or enlarged prostate.
What is the main antihistamine used for nausea?
promethazine (dopamine receptor antagonist)
prevent nausea associated with anesthesia or surgery, or prophylax motion sickness.
Black box warning for promethazine?
Gangrene due to excessive CNS depression ?
Respiratory failure.
What is the most commonly used general purpose anti-nausea/anti-emetic?
Dopamine receptor antagonists (eg. phenothiazine)
Also used for migraine associated nausea.
Example of phenothiazine, and receptors/ properties?
Prochlorperazine
block D2 at CTZ, but also have M1 and H1 so it has sedative properties
Common uses of prochlorperazine>
Phenothiazine (D2 antagonists)
prevent/control of nauseaand vomiting
prophylax motion sickness
migraine nausea
chemotherapy-induced emesis
Adverse effects of prochloroperazine?
TARDIVE DYSKINESIA (involuntary movements)
BLACKBOX - dementia-related psychosis
