Drugs - Metabolism and stuff

Question 1

Warfarin - Cytochrome

Answer 1

2C19

Question 2

Steady state kinetics

Answer 2

Takes 5 half-lives to achieve, then 5 half-lives to clear

Question 3

Most protein bound drugs

Answer 3

Phenytoin, fosphenytoin

Question 4

Antidotes:

INH
Organophosphate

Answer 4

INH: Pyridoxine
Organophosphate: Atropine

Question 5

Toxic alcohols

Answer 5

Methanol - AG, osmolal gap. Blindness, formic acid.
Ethanol - AG, osmolal gap. Respiratory depression, acetate.
Isopropanol - Osmolal gap.
Ethylene glycol - AG, osmolal gap. Oxalate crystals.

Question 6

Zero-order kinetics drugs

Answer 6

Phenytoin
Ethanol
Aspirin

Question 7

Volume of distribution

Answer 7

High for lipophilic drugs. The theoretical volume in which the drug would need to be distributed to match the PLASMA concentration.

Question 8

Drug testing methods

Answer 8

Screening: Immunoassay

Confirmatory: Chromatography + mass spec

Question 9

Cocaine

Answer 9

Coronary vascoconstriction, MI, septal perforation. SNS prodrome.

Benzoylecgonine

Question 10

Opiates

Answer 10

Pinpoint pupils, bradycardia/hypotension.

Many metabolites…

Question 11

Whole blood ethanol

Answer 11

Tends to run lower than serum or plasma ethanol. Conversion is difficult (depends on hematocrit)

Question 12

Odors:

Garlic
Bitter almond
Mothball

Answer 12

Garlic - Arsenic, organophosphates
Almond - Cyanide
Mothball - Camphor

Question 13

Lead poisoning

Answer 13

Inhibits ALA-D and ferrocheletase&raquo_space; ZEP accumulates

Microcytic anemia with basophilic stippling

Treat with dimercaprol

Question 14

Carbon monoxide

Answer 14

Cherry-red appearance. Levels up to 2-6% normal in smokers.

Pulse oximetry may yield normal result–use co-oximetryh.

Question 15

Cyanide poisoning

Answer 15

Cyanide inhibits cytochrome A3&raquo_space; severe lactic acidosis

Treat with amyl nitrite&raquo_space; forms methemoglobin

Question 16

Salicylate poisoning

Answer 16

Metabolic alkalosis with vinegary smell

Also causes respiratory alkalosis

Question 17

Arsenic poisoning

Answer 17

Inhibits oxidative phosphorylation.

Acute symptoms nonspecific. Rice-water diarrhea?

Organic arsenic is common in seafoods–harmless?

Question 18

TCA poisoning

Answer 18

QRS prolongations, arrhythmias

Antichonlinergic effects: Dry/hot/mad

Question 19

Digoxin

Answer 19

Primarily renally secreted.

Many cross-reacting substances.

Antidote: Fab fragments

Question 20

Magnesium poisoning

Answer 20

Inhibits COMT, causing hypersympathetic picture. Resembles pheochromocytoma!

Question 21

CYP inducers

Answer 21

Carbamazepine
Rifampin
Alcohol
Phenytoin
Smoking

CRAPS

Question 22

CYP inhibitors

Answer 22

Ritonavir
Azoles
Grapefruit juice

RAG

Question 23

What drugs are not commonly tested on screening immunoassays?

Answer 23

Oxycodone
LSD and derivatives
GHB
Mephedrone

Question 24

Pseudocholinesterase assay

Answer 24

Diagnostic test for organophosphate poisoning

Question 25

Mephedrone

Answer 25

Primary ingredient of bath salts

Cathinone, derived from Khat (related to amphetamine)

Question 26

Serum separator tubes

Answer 26

May adsorb drugs; use red-top for drug monitoring

Question 27

Codeine metabolism

Answer 27

Metabolized by CYP2D6 into morphine