GI Drugs Flashcards
Name the major receptors involved in nausea/vomiting. (7)
H1, M1, chemoreceptors, D2, NK1, 5-HT3, mechanoreceptors
Scopolomine’s best application for N/V?
Prophylactic
What antihistamine is often used for Meniere’s Disease?
Meclizine (Antivert)
Name 2 highly emetogenic chemotherapeutic drugs.
Cisplatin, Cyclophosphamide
What drug class is the “biggest player” in an antiemetic regimen for chemotherapy-induced N/V? What can you add for higher levels of N/V?
5HT3 antagonist; corticosteroid and Aprepitant (NK1 antag)
What drug class is the cornerstone of chemotherapy anti-emesis regimens?
5-HT3 antagonists
Which 5-HT2 Antagonist has a half-life of 40 hours and is effective for delayed emsis?
Palonosetron
What antiemetic class can have major P450 enzyme interactions?
Neurokinin Receptor-1 antagonists
Name 2 NK-1 antagonists
Aprepitant
Netupitant
What is the advantage of CINVANTI over fosaprepitant?
It is a lipid emulsion of aprepitant rather than a prodrug like fosaprepitant and can be given by IV push rather than as a 30 minute infusion
What is Akynzeo?
A combination of (fos)netupitant (NK-1 antag) and palonosetron (5-HT3 antag); both drugs have a longer half-life; this prep can be given IV or PO
Name some D2 dopamine receptor antagonists used as antiemetics.
Benadryl
Phenergan
Benzos
Reglan
What are 2 contraindications for the use of laxatives?
Fecal impaction
Bowel obstruction
Name some bulk-forming laxatives.
Methylcellulose, Psyllium (Metamucil, Citrucel)
What drug class is the agent of choice for relief of temporary constipation?
Bulk-forming laxatives; safest class
Name some surfactant laxatives
Docusate salts, colace
Describe the MOA of surfactant laxatives
Anionic surfactant (soap-like) allows oil and water to penetrate stool
What is the most abused class of laxatives?
Stimulant laxatives; eating disorders
Name some stimulant laxatives
Bisacodyl (Dulcolax, Correctol), Senna (Ex-Lax, Senokot), Castor Oil
What mechanism of stimulant laxatives can lead to a common side effect?
Direct stimulation of GI motility can lead to severe stomach cramping
What class of laxatives is used for bowel prep?
Osmotic laxatives
Name some subclasses and drugs of osmotic laxatives.
Magnesium Salts (Milk of Magnesia) Polyethylene Glycol/PEG (Miralax, GoLytely)
What is a concern with osmotic laxatives for older and renal-impaired patients?
Hypermagnesemia with Mg2+ salts
What are 3 characteristics of the antimotility/antisecretory agent Bismuth (Pepto-Bismol)?
Antimotility
Anti-inflammatory
Antimicrobial
What formulation of diphenoxylate (chemically related to meperidine) decreases its abuse potential?
Combination with atropine
What antimotility/antisecretory agent similar to diphenoxylate has NO abuse potential?
Loperamide
Name two common demographics that experience IBS.
Onset younger than 35 years old and female
What tricyclic antidepressant is most commonly used at subtherapeutic doses for IBS-D?
Amitriptyline
What is an advantage of lubiprostone, a prostaglandin analog, used for IBS-C?
Very low systemic absorption
Name an NHE3 inhibitor used for IBS-C.
Tenapanor (IBSRELA)
What is the MOA of tenapanor?
An NHE3 inhibitor; inhibits sodium reabsorption in the SI and colon, resulting in increased water secretion
What opioid is used for IBS-D and associated with gallbladder issues?
Eluxadoline
What antibiotic-derived drug is the first-line treatment for IBS-D?
Rifaximin (works against anaerobic and gram-negative bacteria including C. diff)
What drug class for inflammatory bowel disease exists mainly as prodrugs which are activated in the colon by bacteria?
5-Amino Salicylic Acid (5-ASA)
Name 3 5-ASA prodrugs which are activated in the late SI/colon.
Sulfasalazine, Olsalazine, Balsalazide, Mesalamine (if given as a delayed-release formulation)
What is the primary mechanism of 5-ASA drugs?
Inhibit cyclooxygenase 1 and 2 (topically, not systemically) and reduce production of inflammatory prostaglandins and cytokines in intestines
What glucocorticoid is used for IBD?
Budesonide
What is the MAJOR aggressive factor leading to PUD?
H. pylori
What is the major goal of PUD therapy?
Eradicate H. pylori
What receptors on the gastric parietal cells lead to increased acid production?
ACh (with vagal stimulation)
Histamine
Gastrin
What is the role of pepsin in PUD?
Pepsin is a proteolytic enzyme most active at a pH around 2; when the mucosal barrier is compromised, pepsin will digest the gastric tissue and degrade fibrin clots, promoting GI bleeding
What are the first line antibiotics used to eradicate H. pylori?
Amoxicillin and clarithromycin
What are the 3 steps in PUD therapy?
Eradicate H. pylori
Suppress acid production/activity
Enhance mucosal defenses
What is the most commonly used H2 receptor antagonist?
Famotidine
What is the MOA of H2 receptor antagonists?
Competitively antagonize H2 receptor on gastric parietal cell causing a modest reduction in acid production
What is the H2 receptor antagonist application in anesthesia?
Use of H2 receptor antagonists can raise the pH of gastric secretions such that bacteria that would normally be killed at a lower pH can cause pneumonia with aspiration
In what population should H2 receptor agonist doses be reduced?
Renal insufficiency
For what drugs can H2RAs decrease absorption due to higher pH?
Itraconazole
Iron
What antacid drug can cause a harmless increase in serum creatinine?
H2RAs
What drug class is more effective than H2RAs in reducing acid secretion?
PPIs
What is the mechanism of many drug interactions with PPIs?
Some PPIs are CYP2C19 substrates and inhibitors
What is a major DDI for PPIs?
Plavix (clopidogrel), a prodrug, can fail to activate since PPIs may inhibit CYP2C19 of which Plavix is a substrate.
What is given in PUD “Triple Based Therapy”?
PPI + 2 ABs
What 2 ABs are usually given in PUD therapy?
Clarithromycin and amoxicillin
What can be substituted for amoxicillin in PUD therapy with a PCN allergy?
Metronidazole
What is added to “Triple Therapy” for PUD in “Quadruple Therapy”?
Bismuth 525 mg PO QID
What is the major DDI with sucralfate?
Sucralfate can decrease the absorption of quinolone ABs (ex., ciprofloxacin) due to chelation by aluminum (component of sucralfate)
DO NOT administer these ABs within 2 hours of sucralfate
What is a teaching point for patients taking bismuth?
May cause discoloration of mucus membranes and darkening of stool which could be confused for GI bleed
What is the major CI for mistoprosol?
Pregnancy Category X - abortifacient!!!!
What is mistoprosol?
A PGE analog
What is the pegylated version of naloxone used to decrease GI motility?
Naloxegol oxalate
Why is naloxegol oxalate pegylated?
Adds a positive charge to the molecule, making it unlikely to cross the BBB, decreasing potential for abuse
What is another property of naloxegol oxalate which makes it unlikely to penetrate the CNS (besides PEGylation)
Pgp substrate
What is the anesthetic/analgesic implication of a patient taking a Pgp inhibitor with naloxegol oxalate?
A Pgp inhibitor will allow naloxegol oxalate into the brain so it may prevent the analgesic effects of a drug such as morphine
