Causes of gastroesophageal reflux
- Lower esophageal sphincter - inappropriate relaxation, low resting tone, anatomical alteration
- Acid hypersecretion
- Decreased acid clearance due to impaired peristalsis or abnormal saliva production
- Delayed gastric emptying and/or duodenogastric reflux of bilee salts and pancreatic enzymes
GERD lifestyle Tx
- Elevate head of bed
- Avoid food/liquid 2-3 hrs before bedtime
- Avoidance of fatty or spicy food
- Avoidance of cigs/alcohol
- Weight loss
- Liquid antacid
Tx of GERD in patients w/o Esophagitis
- Alginic acid antacids
- Promotility drugs - cisapride, metoclopramide
- H2 blockers - cimetidine, ranitidine, famotidine, nizatidine
Tx of GERD of patients w/ esophagitis
- H2 blockers
- H2 recceptor blockers + promotility agent
- Anti-reflux surgery
MOA of promotility drugs to treat GERD?
Promotility drugs prevent acid from sitting in stomach too long
What are the promotility drugs?
SE of promotility drugs?
What is vomiting mediated by?
Chemoreceptor Trigger Zone and Vomiting Center in the Medulla
What is vomiting stimulated by?
Local irritation or CNS stimulation
Metabolic consequences of vomiting?
- Hypochloremic metabolic alkalosis
- Hypokalemia (Kidney reuptake of acid results in K+ loss)
What are the classes of antiemetics?
- Serotonin (5HT3) receptor antagonists
What are the phenothiazines?
The neuroleptic class
MOA of Phenothiazine? Promethazine?
- Prochlorperazine - Dopaminergic receptor antagonist
- Promethazine - H1 anticholinergic
SE of prochlorazine and promethazine?
- Prochlorperazine - Torticollis
- Promethazine - Somnolence
Adverse effects of Benzamide derivatives?
Extrapyramidal Syx (but ont as severe phenothiazines)
What are the Benzamide derivatives?
MOA of Trimethobenzamide and Metochlopramide?
- Trimethobenzamide - unknown effects on CRTZ
- Metochlopramide - CNS and peripheral dopaminergic receptor antagonism
MOA of THC?
Suppress the CRTZ by probable anticholinergic mechanism
What are the 5HT3 blockers?
Ondansetron, Granesitron, Dolasetron
Adverse SE of 5HT3 antagonists?
Headache, dizziness, somnolence
Tx strategy for gastroparesis?
Metochlopramide, cisapride, domperidone
5 Types of diarrhea?
- Secretory - Na and Cl secretion/decreased reabs
- Osmotic - Nonabs molecules in gut lumen
- Inflammatory absorptive surface - Destruction of mucosa, impaired abs, outpouring of blood, mucus
- Decreased abs - impaired reabs of electrolytes
- Motility disorder - Increased motility/decreasd motility with bacterial growth
What are the goals to treat diarrhea?
Decrease GI secretion and decrease GI motility
What are the classes for diarrhea Tx?
- Opioid Agonists
Anticholinergic drugs to treat diarrhea?
MOA of loperamide?
Immodium! increase rectal tone and disrupt peristalsis via mu receptor
MOA of diphenoxylate and codeine sulfate?
Mu-R agonist causing contraction of circular muscle "segmentation"
What are the colloids and pectins and what is their MOA?
- Colloid - Metamucil
- Pectin - Kaopectate
Bulk up stool
What is the treatment for constipation?
Laxatives or cathartics
What are the classes of treatments for constipation?
- Osmotic cathartics
- Bluk-forming (hydrophilic colloids)
- Lubricants and fecal softeners