Chapter 7: Medicines and Pharmacology Flashcards by Minh Nguyen

Drug admin: do not pass through liver first (no first-pass metabolism)

Sublingual and rectal drugs

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Drug admin: based on lipid solubility through the epidermis

Skin absorption

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Drug admin: restricted to nonionized, lipid-soluble drugs

CSF absorption

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Largely responsible for binding drugs (PCNs and warfarin 90% bound)

Albumin

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Will displace unconjugated bilirubin from albumin in newborns (avoid in newborns)

Sulfonamides

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Where are tetracycline and heavy metals stored?

In bone

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Constant amount of drug is eliminated regardless of dose

Zero order kinetics

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Drug eliminated proportional to dose

First order kinetics

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How many half-lives for a drug to reach steady state?

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Amount of drug in the body divided by the amount of drug in plasma or blood.

Volume of distribution

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Drugs with a high volume of distribution: extravascular vs intravascular concentratoins

High volume of distribution: higher concentrations in extravascular compartment (e.g., fat tissue) compared with intravascular concentrations

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Fraction of unchanged drug reaching the systemic circulation

Bioavailability

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Bioavailability intravenous drugs

100% bioavailability IV drugs, less other routes (e.g., oral)

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Drug level at which desired effect occurs in 50% of patients

ED-50

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Drug level at which death occurs in 50% of patients

LD-50

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Effect at an unusually low dose

Hyperactive

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Tolerance after only a few doses

Tachyphylaxis

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Dose required for effect

Potency

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Ability to achieve result without untoward effect

Efficacy

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Drug metabolism: components of Phase 1

Demethylation, oxidation, reduction, hydrolysis reactions (mixed function oxidases, requires NADPH/oxygen)

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Drug metabolism: components of Phase 2

Glucuronic acid (#1) and sulfates attached (forms water-soluble metabolite); usually inactive and ready for excretion.

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Def: biliary excreted drugs may become deconjugated in intestines with reabsorption, some in active form

Entero-hepatic recirculation (eg, cyclosporine)

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Inhibitors of p-450

Cimetidine. Isoniazid. Ketoconazole. Erythromycin. Cipro. Flagyl. Allopurinol. Verapamil. Amiodarone. MAOIs. Disfulfiram.

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Inducers of p-450

Cruciform vegetables. ETOH. Insecticides. Cigarette smoke. Phenobarbital (barbiturates). Dilantin. Theophylline. Warfarin.

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Most important organ for eliminating most drugs (glomerular filtration and tubular secretion)

Kidney

- Ionized - Water soluble - More likely to be eliminated in unaltered form

Polar drugs

- Non-ionized - Fat soluble - More likely metabolized before excretion

Nonpolar drugs

Caused by uric acid build up | - End product of purine metabolism

Gout

Anti-inflamamtory | - Binds tubulin and inhibits migration of WBCs

Colchicine

- NSAID | - Inhibits prostaglandin synthesis (reversible cyclooxygenase inhibitor)

Indomethacin

- Xanthine oxidase inhibitor | - Blocks uric acid formation from xanthine

Allopurinol

Increases renal secretion of uric acid

Probenecid

Binds bile acids in gut, forcing body to resynthesize bile acids from cholesterol, thereby lowering body cholesterol; can bind vitamin K and cause bleeding tendency

Cholecystramine (lipid-lowering agents)

- Statin drugs - Can cause liver dysfunction - Rhabdomyolysis

HMG-CoA Reductase Inhibitors

- Inhibits cholesterol synthesis - Can cause flushing - Tx: ASA

Niacin

- Inhibits dopamine receptors - SE: tardive dyskinesia - Tx: diphenhydramine (Benadryl)

Promethazine (Phenergan, antiemetic)

- Inhibits dopamine receptors | - Can be used to increase gastric and gut motility

Metoclopramide (Reglan, prokinetic)

Central-acting serotonin receptor inhibitor

Ondansetron (Zofran, antiemetic)

- Proton pump inhibitor | - Blocks H/K ATPase in stomach parietal cells

Omeprazole

Histamine H2 receptor blockers | - Decrease acid in stomach

Cimetidine / ranitidine

Long-acting somatostatin analogue | - Decreases gut secretions

Octreotide

- Inhibits Na/K ATPase and increases myocardial calcium - Slows atrial-ventricular conduction - Inotrope - Not cleared with dialysis - SE: Visual changes (yellow hue), fatigue, arrhythmias

Digoxin

Why has digoxin been implicated in causing mesenteric ischemia?

Decreases blood flow to intestines

- Good for acute atrial and ventricular arrhythmias | - SE: pulmonary fibrosis w/ prolonged use; can also cause hypo- and hyperthyroidism

Amiodarone

Used to treat tornadoes de pointes (ventricular tachycardia)

Magnesium

Causes transient interruption of the AV node

Adenosine

- Best single agent shown to improve survival in patients with CHF - Can prevent CHF after MI - Can prevent progression of renal dysfxn in pts with HTN and DM. - Can precipitate renal failure in patients with renal artery stenosis

ACE inhibitors | angiotensin-converting enzyme inhibitors

What increases the sensitivity of the heart to digitalis?

Hypokalemia | - Can precipitate arrhythmias or AV block

- May prolong life in patients with severe LV failure | - Reduce risk of MI and atrial fibrillation post

Beta blockers

Best single agent shown to improve survival after myocardial infarction

Beta-blockers

- Acetylcholine antagonist | - Increases heart rate

Atropine

- Inhibit adrenal steroid synthesis | - Used in patients with adrenocortical CA

Metyrapone and aminoglutethimide

- analogue of GnRH and LHRH - Inhibitors release of LH and FSH form pituitary when given continuously (paradoxic effect) - Used in patients with metastatic prostate CA

Leuprolide

Inhibits prostaglandin synthesis and leads to decreased mucus and HCO3- secretion and increased acid production (mechanism of ulcer formation)

NSAIDs

a PGE1 derivative; a protective prostaglandin used to prevent peptic ulcer disease; consider use in patients on chronic NSAIDs

Misoprostol

- Antipsychotic - Inhibits dopamine receptors - Can cause extrapyramidal manifestations (Tx: benadryl)

Haldol

Tinnitus, headaches, nausea, and vomiting.

ASA poisoning

Two manifestations of aspirin poisoning

1st: respiratory alkalosis 2nd: metabolic acidosis

MC side effect of gadolinium

Nausea

Iodine: - MC side effect? - MC side effect requiring medical treatment?

Iodine: - MC side effect: nausea - MC side effect requiring medical treatment: dyspnea

Tx: tylenol overdose

N-acetylcysteine

pharmacokinetics principles

``` dissolution absorption distribution metabolism secretion ```

mechanism of cholestyramine

bind of bile acids and prevent reabsorption?

mechanism of weight loss medication?

sibutramine --> inhibition of neurotransmitter reuptake orlistat --> bind and inhibits gastric and pancreatic lipases --> prevent absorption of free fatty acid and decrease triglycerides production