Drugs - enzymes and transporters

Question 1

What is an enzyme inhibitor?

Answer 1

a molecule that binds to anenzymeand (normally) decreases itsactivity

Question 2

How does an enzyme inhibitor work?

Answer 2

An enzyme inhibitor prevents the substratefrom entering the enzyme’sactive site and prevents it fromcatalyzingits reaction

Question 3

What are the 2 types of enzyme inhibitors?

Answer 3

Irreversible
Reversible

Question 4

How do irreversible inhibitors work?

Answer 4

usually react with the enzyme and change it chemically (e.g. viacovalent bondformation)

Question 5

How do reversible inhibitors work?

Answer 5

bindnon-covalentlyand different types of inhibition are produced depending on whether these inhibitors bind to theenzyme, the enzyme-substrate complex, or both

Question 6

What does inhibiting ACE do?

Answer 6

Decreases RAAS system, reduces angiotensin II, so less Na+ and water retained, lowers BP

Question 7

What does inhibiting HMG-CoA reductase do?

Answer 7

Rate limiting step, reduced cholesterol production

Question 8

What are the passive ways of transporting drugs and ions?

Answer 8

Symporter
Channels

Question 9

What ions travel by symporters?

Answer 9

Na/K/2Cl
NaCl

Question 10

What ions travel by channels?

Answer 10

Na
Ca
K
Cl

Question 11

What is the active way of transporting drugs and ions?

Answer 11

ATP-ases

Question 12

What ions travel through ATP-ases?

Answer 12

Na/K
K/H

Question 13

What are the 3 main protein ports?

Answer 13

Uniporters
Symporters
Antiporters

Question 14

What do uniporters do?

Answer 14

Use energy from ATP to pull molecules in

Question 15

What do symporters do?

Answer 15

use the movement in of one molecule to pull in another molecule against a concentration gradient

Question 16

What do antiporters do?

Answer 16

one substance moves against its gradient, using energy from the second substance (mostly Na+, K+ or H+) moving down its gradient

Question 17

What’s an example of a symporter?

Answer 17

NKCC (Na K Cl co transporter)

Question 18

What does furosemide do?

Answer 18

Inhibits luminal NKCC symporter in LOH causing Na, K, Cl to be lost in urine

Question 19

What are examples of ion channels?

Answer 19

• Epithelial (Sodium): heart failure
• Voltage-gated (Calcium, Sodium): nerve, arrhythmia
• Metabolic (Potassium): diabetes
• Receptor Activated (Chloride): epilepsy

Question 20

What’s are examples of ATP-ases?

Answer 20

Sodium pump (Na/K ATP-ase)
Proton pump (K/H ATP-ase)

Question 21

What is digitoxin?

Answer 21

1. inhibits the Na+/K+ ATPase, mainly in the myocardium
2. This inhibition causes an increase in intracellular Na, resulting in decreased activity of the Na-Ca exchanger and increases intracellular Ca
3. This lengthens the cardiac action potential, which leads to a decrease in heart rate

Question 22

What is digitoxin used for?

Answer 22

atrial fibrillation, atrial flutter, and heart failure

Question 23

What does omeprazole do?

Answer 23

Is an irreversible inhibitor of H/K ATP-ase
Is a PPI (proton pump inhibitor)

Question 24

What are organophosphates?

Answer 24

Irreversible inhibitors of cholinesterase

Question 25

What are some examples of organophosphates?

Answer 25

- Insecticides (Diazinon) - Nerve gases (Sarin)

Question 26

What are the muscarinic and nicotinic effects of organophosphates?

Answer 26

- Muscarinic – salivation, defaecation, urination, bradycardia, hypotension - Nicotinic – twitching, severe weakness paralysis, diaphragm

Question 27

What are the effects on the CNS from organophosphates?

Answer 27

confusion, loss of reflexes, convulsions, coma

Question 28

What is simvastatin?

Answer 28

A statin (enzyme)

Question 29

What is ramipril?

Answer 29

ACE inhibitor (enzyme)

Question 30

What is aspirin?

Answer 30

COX inhibitor (IRREVERSIBLE enzyme inhibitor)

Question 31

What is paracetamol?

Answer 31

COX inhibitor (enzyme)

Question 32

What determines the duration and intensity of a drug?

Answer 32

Rate of metabolism

Question 33

What are the major enzymes involved in drug metabolism?

Answer 33

CYPs (eg. CYP450) involved in 75% drug metabolism

Question 34

What are ENaCs (epithelial Na channels)?

Answer 34

Causes reabsorption of Na+ ions at the collecting ducts of the kidney's nephrons (also in colon, lung and sweat glands)

Question 35

What drug targets ENaCs?

Answer 35

Amiloride Thiazide Work as anti-hypertensive

Question 36

Where are VDCCs (voltage gated Calcium channels) found?

Answer 36

found in the membrane of excitable cells (e.g. muscle, glial cells, neurons, etc.) At physiologic or resting membrane potential, VDCCs are normally closed

Question 37

What drug targets VDCCs?

Answer 37

Amlodipine - Causes vasodilation and a reduction peripheral vascular resistance, lowering blood pressure - Also prevents excessive constriction in the coronary arteries

Question 38

How do receptor-mediated (chloride) channels work?

Answer 38

Ligand-gated ion channels (ionotropic receptors), open to allow ions to pass through the membrane in response to the binding of a chemical messenger (i.e. a ligand) such as a neurotransmitter an example of receptor is GABA -A Receptor

Question 39

What drug works on receptor-mediated (chloride) receptors?

Answer 39

Barbiturates increase the permeability of the channel to chloride on GABA A receptors