83. Drug Interactions

Front 1

When two drugs interact the combined effect can be?

(three possibilites)

Back 1

Additive – the combined effect is higher that either of the individual effects but not higher than the sum of the two individual effects

Potentiated (potentiation) – the combined effect is higher than the sum of the two individual effects

Antagonized – the combined effect is smaller than that of one of the individual effects

Front 2

Name some drug types with small margins of safety.

Back 2

Anticoagulants

Antiarrhythmic drugs

Cytotoxic drugs

Antiepileptic drugs

Antidiabetic drugs

Cardiac glycosides

Front 3

Drug interactions that lead to increased effect of the drug are most dangerous when the drug has a certain property. What property?

Back 3

Drug interactions that lead to increased effect of the drug are most severe when the drug has a small margin of safety.

Front 4

Drug interactions that lead to decreased effect of the drug are most dangerous when the disease the drug treats has a certain property. What property?

Back 4

Drug interactions that lead to decreased effect of the drug are most dangerous when the disease the drug treats is sensitive to undertreatment.

Front 5

Name some conditions which are sensitive to undertreatment.

Back 5

Arrhythmias

Epilepsy

Serious infections

Front 6

What properties do drugs which can displace other drugs from plasma proteins have?

Back 6

Drugs which are highly plasma protein bound but not very potent can effectively displace other drugs

Front 7

What properties do drugs which can be displaced from plasma proteins by other drugs have?

Back 7

Drugs which are highly plasma protein bound but very potent cannot effectively displace other drugs, but they can themselves be displaced

Front 8

Name some drugs which often displace other drugs from plasma proteins.

Back 8

Aspirin

Sulphonamides

Valproate

Front 9

Name some drugs which are often displaced from plasma proteins by other drugs.

Back 9

Coumarins

Phenytoin

NSAIDs

Front 10

What is the function of P-glycoprotein (Pgp)?

Back 10

P-glycoprotein (Pgp) is a transport protein which pumps drugs out from organs which require extra protection against foreign substances, like the brain, placenta and testicles. It’s also found in kidney tubules, the GI tract and in bile ducts, where it contributes to drug excretion.

Front 11

Name some drugs which are substrates for Pgp.(often asked on exam)

Back 11

Colchicine, Cyclosporine, Digoxin, Fexofenadine, Morphine, Tacrolimus

Front 12

Name some drugs which inhibit Pgp.

Back 12

Amiodarone, Clarithromycin, Cyclosporine, Erythromycin, Ketoconazole, Quinidine, Verapamil

Front 13

Name some drugs which induce Pgp.

Back 13

Rifampin, chlorpromazine, St. John's wort.

Front 14

What is the result of induction of the enzyme which metabolizes a prodrug?

Back 14

More of the prodrug is converted into the active metabolite, so the pharmacological effect increases.

Front 15

What is the result of induction of the enzyme which metabolizes an active drug (not a prodrug)?

Back 15

More of the drug is converted into an inactive metabolite, so the pharmacological effect decreases.

Front 16

What is the result of inhibiton of the enzyme which metabolizes an active drug (not a prodrug)?

Back 16

Less of the drug is converted into an inactive metabolite, so the pharmacological effect increases.

Front 17

What is the result of inhibition of the enzyme which metabolizes a prodrug?

Back 17

Less of the prodrug is converted into the active metabolite, so the pharmacological effect decreases.

Front 18

Name some prodrugs.

Back 18

Codeine, tamoxifen, clopidogrel

Front 19

Name some drugs which are typical enzyme inducers

Back 19

Phenytoin, carbamazepine, phenobarbital, rifampin, etc.

Front 20

Name some drugs which are typical enzyme inhibitors.

Back 20

Ketoconazole, amiodarone, erythromycin, allopurinol, verapamil, cimetidine

Front 21

Name some substrates for organic anion transporter (OAT)

Back 21

NSAIDs, penicillins, cephalosporins, thiazides, loop diuretics

Front 22

Name some substrates for organic cation transporter (OCT)

Back 22

Metformin

Cimetidine

Amiloride

Front 23

Administration of sodium bicarbonate makes the urine more basic. This increases the excretion of what types of drugs?

Back 23

Weak acids, like salicylates and phenobarbital

Front 24

Administration of ammonium chloride makes the urine more acidic. This increases the excretion of what types of drugs?

Back 24

Weak bases, like quinidine

Front 25

How can drug interactions occur at the level of renal excretion?

Back 25

Drugs which are secreted into the tubules by the same transporter protein (OAT, OCT, Pgp) can compete with each other for secretion.