Flashcards in Pharmacology Deck (16)
Mechanism of ribavirin?
- incorporated into RNA as purine and pairs equally well with U and C, leading to hypermutation and lethality
- depletes intracellular GTP (prevents 5' capping)
- direct inhibition of viral polymerase
- enhances immune response
Side effect of mu opioid analgesics that results in right upper quadrant pain?
contraction of smooth muscle in the sphincter of Oddi leading to constriction and spasm
increased pressures in bile duct and gall bladder can lead to rare, painful crisis called biliary colic
Most common cause of duodenal ulcer? Treatment?
H. pylori (80-95% of cases)
remaining cases associated with NSAID use
- antibiotics to eradicate H.pylori (metronidazole, tetracycline, amoxicillin, clarithromycin)
- adjunctive agent like a proton pump inhibitor or bismuth
What is polyethylene glycol? What is the mechanism? Name other drugs in this class.
(magnesium hydroxide, magnesium citrate, lactulose)
provides osmotic load to draw water out
used for constipation
How to calculate oral bioavailability if you have oral and IV plasma concentrations of drug? What is bioavailability of an IV administered drug?
(area under curve for oral admin.) / (area under curve for IV admin.)
IV-administered frug has 100% bioavailability!
Name the H2-blockers. What are they used for?
Cimetidine, ranitidine, famotidine, nizatidine
"Take H2 blockers before you DINE. Table for 2 (H2)."
Uses: peptic ulcer, gastritis, mild esophageal reflux
H2 blocker side effects?
- potent inhibitor of cytochrome P-450
- antiandrogenic effects (prolactin release, gynecomastia, impotence, decreased libido in males)
- crosses BBB (confusion, dizziness, headaches) and placenta
Cimetidine and ranitidine:
- decreased renal excretion of creatinine
Other H2-blockers are relatively free of these effects
Where is iron absorbed in the GI?
predominantly in the duodenum and proximal jejunum
35yo with colicky abdominal pain, constipation, irritability, works in battery manufacturing? What are the classic symptoms? Treatment?
Lead lines on gingivae (Burton lines) and on metaphyses of long bones on X-ray
Encephalopathy and Erythrocytes basophilic stippling
Abdominal colic and sideroblastic Anemia
Drops (wrist and foot drop)
Dimercaprol and EDTA
Succimer used for chelation in kids (SUCks to be a kid that eats lead)
Pt presents with vomiting, abdominal pain, garlic breath. What is the treatment for arsenic poisoning?
also treats mercury and gold poisoning
What is the treatment for iron poisoning from repeated transfusions?
What is the treatment for cyanide poisoning?
Nitrites (like amyl nitrite) + thiosulfate, hydroxocobalamin
forms methemoglobin that binds cyanide ions with high affinity, thus preventing cyanide from binding mitochondrial enzymes in the tissues
What is the treatment for methemoglobin?
methylene blue, vitamin C
methylene blue is a reducing agent that converts iron in heme from the Fe3+ state to the Fe2+ state
How do loperamide and diphenoxylate treat diarrhea?
mu opiate anti-diarrheal
binds mu opiate receptors in GI tract and slows motility
What is secretory diarrhea and what drugs are used to treat it?
due to excess secretions of fluids and electrolytes in the gut
Treatments: octreotide (somatostatin analogue), bismuth, probiotics