7: Medicines and Pharmacology Flashcards
What is the best single agent shown to improve survival after myocardial infarction?
Beta-blockers
[Beta-blockers may prolong life in patients with severe left ventricular heart failure. They also reduce the risk of MI and atrial fibrillation postoperatively.]
What are two potential serious side effects of long-term amiodarone use?
- Pulmonary fibrosis
- Hypo/hyper-thyroidism
What is the volume of distribution of a drug?
Amount of drug in the body divided by the amount of drug in the plasma/blood
[A drug with a high volume of distribution has a higher concentration in the extravascular compartment (eg fat tissue) compared with intravascular concentrations.]
What is the mechanism of action of Misoprostol and what is it used for?
Misoprostol is a PGE1 derivative, a protective prostaglandin used to prevent peptic ulcer disease
[Its use is considered in patients on chronic NSAIDs.]
Nonintravenous drugs delivered via which two routes avoid first pass metabolism in the liver?
- Sublingual
- Rectal
How does Digoxin work?
It inhibits the Na/K ATPase and increases myocardial calcium which slows atrial-ventricular conduction
[It also decreases blood flow to the intestines (it has been implicated in mesenteric ischemia). Hypokalemia increases sensitivity of the heart to digitalis, precipitating arrhythmias or AV block. Digoxin is not cleared with dialysis.]
What is the median lethal dose (LD50)?
LD50 = Drug level at which death occurs in 50% of patients
Which drugs inhibit P-450?
- Cimetidine
- Isoniazid
- Ketoconazole
- Erythromycin
- Ciprofloxacin
- Flagyl
- Allopurinol
- Verapamil
- Amiodarone
- MAOIs
- Disulfuram
What is the bioavailability of a drug?
The fraction of a drug that reaches the systemic circulation unchanged
[The bioavailability of intravenous drugs is assumed to be 100% and less for other routes of administration.]
Why should Sulfonamides be avoided in newborns?
Sulfonamides displace unconjugated bilirubin from albumin in newborns
What are the symptoms and signs of ASA poisoning
- Symptoms: Tinnitus, headaches, nausea, vomiting
- Signs: First respiratory alkalosis followed by metabolic acidosis
What is the mean effective dose (ED50) of a drug?
ED50 = drug level at which desired effect occurs in 50% of patients
What is the best single agent shown to improve survival in patients with congestive heart failure?
ACE inhibitor
[ACE-inhibitors can prevent CHF after myocardial infarction. They can prevent progression of renal dysfunction in patients with hypertension and diabetes mellitus. They can precipitate renal failure in patients with renal artery stenosis.]
How does the drug adenosine work?
It causes a transient interruption of the AV node
What is the mechanism of action of Atropine?
Atropine is an acetylcholine antagonist which increases heart rate
During which phase of drug metabolism dos attachment of sulfates and glucuronic acid occur (making the drug/metabolite water-soluble)?
Phase II
[Phase I drug metabolism includes demethylation, oxidation, reduction, hydrolysis reactions (mixed function oxidases, requires NADPH/oxygen).]
What is the treatment for the flushing side effect associated with Niacin?
Aspirin
What is the rate of elimination of a drug that follows as below?
- Zero-order kinetics:
- First-order kinetics:
- Zero-order kinetics: Constant amount of drug is eliminated regardless of dose
- First-order kinetics: Rate of drug elimination is proportional to dose
What is the treatment for a Tylenol overdose?
N-acetylcysteine
What is the mechanism of action of Leuprolide and what is it used for?
Leuprolide is an analogue of GnRH and LHRH and it is used to inhibit the release of LH and FSH from the pituitary when given continuously (paradoxic effect)
[It is used in patients with metastatic prostate cancer.]
What is the mechanism of action of haloperidol (Haldol)?
Inhibits dopamine receptors
[Can cause extrapyramidal manifestations which can be treated with Benadryl.]
How do the below antiemetics work?
- Promethazine (Phenergan):
- Metoclopramide (Reglan):
- Ondansetron (Zofran):
- Promethazine (Phenergan): Inhibits dopamine receptors (Side effects include tardive dyskinesia which can be treated with Benadryl)
- Metoclopramide (Reglan): Inhibits dopamine receptors (can be used to increase gastric and gut motility)
- Ondansetron (Zofran): Central-acting serotonin receptor inhibitor
90% of penicillins and Warfarin are bound to what?
Albumin
[Albumin is largely responsible for binding drugs.]
What is used to treat Torsades de pointes (ventricular tachycardia)?
Magnesium
What are the 4 drugs used for treating Gout and how do they work?
- Colchicine (Anti-inflammatory): Binds tubulin and inhibits migration of WBCs
- Indomethacin (NSAID): Inhibits prostaglandin synthesis (reversible COX inhibitor)
- Allopurinol (Xanthine oxidase inhibitor): Blocks uric acid formation from xanthine
- Probenecid: Increases renal secretion of uric acid
Which drugs induce P-450?
- Cruciform vegetables
- Ethanol
- Insecticides
- Cigarette smoke
- Phenobarbital
- Phenytoin
- Theophylline
- Warfarin
How many half lives does it take a drug to reach steady state?
5 half lives
How do NSAIDs cause GI ulcers?
They inhibit prostaglandin synthesis and lead to a decrease in mucus and bicarb secretion while also increasing acid production
What do the drugs metyrapone and aminoglutethimide (cytadren) do?
Inhibit adrenal steroid synthesis
[Used in patients with adrenocortical cancer.]
