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