Drug questions

Question 1

Cisplatin is given at night. Why?

Answer 1

That is when urinary output is maximal and reduces renal toxicity.

Question 2

Glucocorticoids are given in morning, why?

Answer 2

This is when cortisol production naturally peaks. This will reduce some side effects of prolonged hyperglycemmia.

Question 3

Statins are given at night, why?

Answer 3

This is when cholesterol synthesis peaks, because in most people, they are fasting at this time.

Question 4

How can ASA, which has t1/2 = 4 hours, exert an effect that lasts for 7 days?

Answer 4

It is an irreversible COX inhibitor, so the effects last as long as the platelet, about 7 days.

Question 5

How is Cromolyn (intal) given and why?

Answer 5

Inhalation, because it has a bioavailability of <10% orally. An asthma med

Question 6

What to worry about with Digoxin absorption

Answer 6

Dietary fibers bind to Digoxin, reducing absorption.

Question 7

What to worry about with Synthroid absorption

Answer 7

Synthroid uses amino acid transporters to move from duodenum to blood. If you eat protein, proteases in the duodenum cleave these into their constituent a.a. and now synthroid has competition for the a.a. transporters.

Question 8

Explain how L-Dopa + Carbidopa works

Answer 8

L-Dopa enters the SNS and crosses the BBB. It is then converted into Dopamine in the brain, but Carbidopa (which can’t cross the BBB) prevents its conversion to Dopamine in the body, preventing arrhythmias, about allowing the treatment of Parkinsonism.

Question 9

Differences between Heparin and Warfarin with regards to placenta?

Answer 9

heparin has a Molecular Weight > 1000, while Heparin’s is only 500. Warfarin can pass through the placental barrier and is fetal toxic.

Question 10

Can succinylcholine pass the placenta?

Answer 10

No, because it is highly polar

Question 11

Can thiopental pass the placenta?

Answer 11

Yes, because it is highly lipid soluble and can cause fetal sedation/apnea.

Question 12

What is relationship of drug half-life to PBP?

Answer 12

Epi weakly bound = 15s

Tolbutamide 96% bound = 6 hour

Question 13

What is the warfarin/ASA interaction?

Answer 13

Typically, Warfarin is 99% bound to PBP.

When ASA is taken, it displaces some Warfarin from PBP, increasing [free] and intensity of action/adverse effects.

Question 14

What is relationship between Sulfonamide abx and bilirubin?

Answer 14

Normally PBPB bind bilirubin in neonates. When Sulonaminde abx are given, the abx competes with bilirubin for PBP and increases its [free] and it enters the CNS producing toxic effects.

Question 15

How would cirrhosis affect Ambien?

Answer 15

Ambien is 92.5% bound. In cirrhosis, make fewer PBP, so drug would be less bound and intensity of response/ toxicity would increase.

Question 16

What is important about tetracycline?

Answer 16

It is deposited into developing bone and teeth, discoloring them.

Question 17

What interaction does quinidine and digoxin have?

Answer 17

Quinidine can displace digoxin from muscle, increasing dig toxicity.

Question 18

Give 4 drug examples of metabolism.

Answer 18

1. Inactivation of Procaine into PABA.
2. Increasing therapeutic effect of codeine into morphine.
3. Activation of prodrug fosphenytoin into phenytoin.
4. Increased toxicity of acetaminophen into metabolite.

Question 19

What is classic example of first pass effect?

Answer 19

NTG, that’s why give it SL.

Question 20

Hydrolytic enzymes

Answer 20

Pseudocholinesterase hydrolyzes succinylcholine and procaine, metabolizing them.

Question 21

Another First Pass drug

Answer 21

Propranolol, so oral dose is much higher

Question 22

2 Prodrugs

Answer 22

Loratadine and naproxen

Question 23

Acetaminophen metabolism

Answer 23

Phase I: CYP reaction produces a toxic metabolite.
Phase 2: This metabolite is quickly conjugated with glutathione.
In OD situations, glutathione is depleted and [metabolite] increases!

Question 24

How does Mucomyst help in acetaminophen OD?

Answer 24

Stimulates synthesis of glutathione.

Question 25

CYP inducers

Answer 25

1. Phenobarbital
2. Tolbutamide
3. Phenytoin
4. Cigs
5. chronic EtOH
6. charcoal cooked food,
7. cabbage
8. Factory workers exposed to nitrates respond poorly to ntg
9. some insecticides in farm workers

Question 26

Dicumarol + Phenobarbital

Answer 26

Dicumarol is an anticoag given to pts that have had strokes. If they then have seizure, we give them phenobarbital (a CYP inducer). This increases metabolism of dicumarol and they can clot more, so must up dose.

Question 27

CYP inhibitor

Answer 27

cemetidine inhibits the metabolism of estradiol, causing gynecomastica in men

Question 28

Why add sulbactam to PCN drugs?

Answer 28

It is an inhibitor of beta lactamases which metabolize PCN

Question 29

Why take disulfiram if an alcoholic?

Answer 29

It inhibits the complete metabolism of EtOH, allowing acetaldehyde to accumulate, which causes vasodilation, HA, n/v

Question 30

Explain how chemical antagonism works

Answer 30

Protamine (a positively charged molecule) binds to Heparin (a negatively charged molecule) preventing Heparin from binding to clotting factors.

Question 31

Explain how physiological antagonism works?

Answer 31

Glucocorticoid therapy causes hyperglycemia that can compromise the effect of insulin.