N+V+D Pharmacology Flashcards
What categories are antidiarrheals divided into?
1) adsorbents (not absorbents)
2) antimotility drugs (anticholinergics and opiates)
3) intestinal flora modifiers (aka probiotics and bacterial replacement drugs)
Adsorbents
How do they work?
How is this different from absorption?
When are they used?
- Coat the walls of the Gi tract and binding the causative bacteria or toxin to their adsorbent surface for elimination from the body through the stool.
- Differs from absorption in that it involves the chemical binding of substances onto the surface of an adsorbent while absorbents involve uptake of substance across a surface
- Used in milder cases
Effect of anticholinergics?
When are they used?
- Slow peristalsis by dec the rhythmic contractions and smooth muscle tone of the GI tract
- Often used in combo w opiates and adsorbents
- Used in more severe cases of diarrhea
How do intestinal flora modifiers work?
Who are these especially useful for?
• Products obtained from bacterial cultures mostly lactobacillus (which make up the majority of the bodys normal bacterial flora and are most commonly killed by Abx.
The intestinal flora modifier will replenish the bacteria and suppress disease causing bacteria
•Helpful for pt w antibiotic induced diarrhea
Do intestinal flora modifiers typically have many adverse effects?
Antidiarrheals in general?
No
•varies but most are minor and not life threatening
How are opiates used as antidiarrheals?
- Dec bowel motility (allowing more absorption and dec stool freq and volume)
- dec pain caused by rectal spasms
- used in more severe cases of diarrhea
diphenoxylate hydrochloride with atropine sulphate
What class?
How does it work?
Opioid
• acts on sm muscle of GI tract to dec GI motility and excess GI propulsion
• little to no analgesic effect
Why is atropine added to diphenoxylate?
added to discourage recreational use (it has cholinergic effects eg dry mouth, abdm pain, tachy when taken in lg doses)
Why do you need to use pepto-bismol w caution with children?
D/t reyes syndrome
Should antidiarrheals be used at home with children?
Always contact doctor first!
What does CTZ stand for in pathway of N+V in brain?
VC?
CHemoceptor Trigger Zones
Vomiting center
How does pathway work in initiation of N+V in brain?
- The VC is area of brain responsible for initiation of the physiological events that lead to N and eventually V
- Neurotransmitter signals are sent to VC from the CTZ (another area of brain involved in induction of N &V
- The signals alert these areas of brain to the nauseating substances that need to be expelled from body
- Once CTZ and VC are stimulated theyll initiate the events that trigger V reflex
What neurotransmitters are involved in N+V?
Ach, dopamine, histamine, prostalgandins, serotonin
What drug that we’re required to know is an example of an Anticholinergic
scopolamine
prochlorperazine
How do anticholinergic drugs work in r/t vomiting?
- Block ACH receptors on vestibular nuclei. When bound this blocks nausea inducing signals and prevents them being transmitted to CTZ. Also blocks signals from getting to vomit centre
- Also tend to dry GI secretions
Scopolamine is commonly used for?
motion sickness, adjunct to anesthesia to inhibit salivation and excess resp secretion, causes amnesia and sedation. Often comes in patch
Neuroleptic drug example?
prochlorperazine
Action of neuroleptics?
- Were used for antipsychotic effect but also prevent N&V by blocking dopamine receptors on CTZ
- Often have anticholinergic effects
