Mention 6 major PPIs.
- Omeprazole
- Esomeprazole
- Dexlansoprazole
- Lansoprazole
- Pantoprazole
- Rabeprazole
What is the mechanism of action of omeprazole?
Irreversible blockade of H+/K+ ATPase in active gastric parietal cells.
What is the clinical use of omeprazole?
- Peptic ulcer disease
- GERD
- Erosive gastritis
What are the pharmacokinetics of omeprazole?
Half-lives much shorter than duration of action.
What are the side effects of omeprazole?
- Low toxicity
2. Reduction of stomach acid may reduce absorption of some drugs and increase that of others.
Mention 4 major H2 blockers.
- Cimetidine
- Famotidine
- Nizatidine
- Ranitidine
Are H2 blockers safe drugs?
Yes - Available OTC.
What is important to keep in mind about cimetidine?
In contrast to other H2 blockers, it is a weak antiandrogenic agent and a potent CYP inhibitor.
What is the sucralfate?
Polymerizes at the site of tissue damage and protects against further damage.
Very insoluble - no systemic effects.
How many times must sucralfate be given?
4x daily.
What are the 4 categories of prokinetic GI agents?
- Metoclopramide
- Domperidone
- Cholinomimetics (neostigmine)
- Macrolides (erythromycin)
What is the mechanism of metoclopramide?
D2 blocker - increases gastric emptying and intestinal motility.
What is the clinical use of metoclopramide?
- Gastric paresis (in diabetes)
2. Antiemetic
What are the pharmacokinetics of metoclopramide?
Oral and parenteral formulations.
What are the side effects of metoclopramide?
Parkinsonian symptoms due to block of CNS D2 receptors.
Mention a drug similar to metoclopramide, but less CNS toxic.
Domperidone
Where are macrolides (erythromycin) used as a prokinetic agent?
In diabetic gastroparesis but tolerance develops.
What is the mechanism of action of magnesium hydroxide, other non absorbable salts and sugars?
Osmotic agents that increase water content of stool.
What is the clinical use of magnesium hydroxide?
Simple constipations - bowel prep for endoscopy (especially PEG (pegylated) solutions).
How is magnesium hydroxide administered?
Orally
What are the side effects of magnesium hydroxide?
Renal impairment.
Mention 2 bulk-forming agents.
- Methylcellulose
2. Psyllium
What do these bulk-forming agents do?
- Increase volume
2. Stimulation evacuation
Mention two stool surfactants.
- Docusate
2. Mineral oil
What do those two stool surfactants do?
- Lubricate stool
2. Ease passage
Mention 2 stimulating stool agents.
Senna and cascara.
What may these stimulating stool agents cause?
Cramping.
Mention 2 chloride channel activators.
- Lubiprostone
2. Prostanoic acid derivative
What is the mechanism of action of chloride channel activators?
Stimulate chloride secretion into intestine, increasing fluid content.
Mention 2 opioid receptor blockers that are used as laxatives.
- Alvimopan
2. Methylnaltrexone
What is the mechanism of action of opioid laxatives?
Block intestinal μ receptors but do not enter CNS, so analgesia is maintained.
What is the mechanism of action of the antidiarrheal loperamide?
Activates μ opioid receptors in enteric nervous system and slows motility with negligible CNS effects.
What is the clinical use of loperamide?
Nonspecific, non infectious diarrhea.
How is loperamide administered?
Orally
What are the side effects of loperamide?
Mild cramping but little or no CNS effect.
Mention a drug similar to loperamide.
Diphenoxylate - at higher doses can cause CNS opioid effects and toxicity.
What is the mechanism of action of alosetron?
5-HT3 blocker of high potency and duration of binding.
–> Reduces smooth muscle activity in GI tract.
What is the clinical use of alosetron?
- Severe diarrhea
2. Predominant IBS in women
How is alosetron administered?
Orally
What are the side effects of alosetron?
- Rare but serious constipation
- Ischemic colitis
- Bowel infarction
Besides alosetron, what other drugs are used for IBS?
- Anticholinergics
2. Chloride channel activator –> Lubiprostone is useful in constipation predominant IBS in women.
Mention the 6 general categories of drugs that are used as antiemetics.
- 5-HT3 blockers
- Corticosteroids
- Antimuscarinics
- Phenothiazines
- Cannabinoids
- Aprepitant
Mention 4 major 5-HT3 blockers.
- Ondasetron
- Dolasetron
- Granisetron
- Palonosetron
What is the clinical use of ondasetron?
Prevention of chemotherapy-induced and post-op nausea and vomiting.
What are the pharmacokinetics of ondasetron?
Oral and parenteral formulations.
What is a possible side effect of ondasetron?
May slow colonic transit.
What is the mechanism of action of corticosteroids as antiemetics?
Not known, but useful in antiemetic IV cocktails.
What antimuscarinic agent do we use as antiemetic?
Scopolamine - effective in emesis due to motion sickness.
What cannabinoid is used as antiemetic?
Dronabinol - for use in chemo-induced nausea and vomiting, but is associated with marijuana effects.
What is the mechanism of aprepitant as an antiemetic?
Neurokinin 1 blocker - for use in chemo-induced nausea and vomiting - associated with fatigue, dizziness, diarrhea, and CYP interactions.
What drugs are used for inflammatory bowel disease?
- Mesalamine
- Azo compounds
- Glucocorticoids
- Immunosuppressant antimetabolites
- Anti-TNF drugs
- Natalizumab
What is the mechanism of action of mesalamine (5-aminosalicylate)?
Uncertain - may be inhibition of eicosanoid inflammatory mediators.
What is the clinical use of mesalamine?
Mild to moderately severe Crohn’s disease and ulcerative colitis.
What are the pharmacokinetics of mesalamine?
Various formulations designed to deliver drug to distal ileum and colon.
What are the side effects of mesalamine?
Little or no toxicity.
What are the main azo compounds use in IBD?
- Dalsalazide
- Olsalazine
- Sulfasalazine
What is the natalizumab?
Antibody that blocks leukocyte integrins - may cause multifocal leukoencephalopathy.
What is the mechanism of action of pancrelipase?
Replacement enzymes from animal pancreatic extracts that improve digestion of fat, protein, and carbohydrate.
What is the clinical use of pancrelipase?
Pancreatic insufficiency due to cystic fibrosis, pancreatitis, and pancreatomy.
What are the pharmacokinetics of pancrelipase?
Taken with every meal.
What is a possible side effect of pancrelipase?
May increase incidence of gout.
What is the mechanism of action of ursodiol?
Reduces cholesterol secretion into bile.
What are the clinical uses of ursodiol?
Gallstones in patients refusing or not eligible for surgery.
How is ursodiol administered?
Orally
What are the side effects of ursodiol?
Little or no toxicity.
What are the 3 main drug categories that are used in acid-peptic diseases?
- Proton pump inhibitors (PPIs)
- H2 blockers
- Antacids