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phase 2a > drugs and enzymes > Flashcards

drugs and enzymes Flashcards

1
Q

what is an enzyme inhibitor?

A

is a molecule that binds to anenzymeand (normally) decreases itsactivity.

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2
Q

what does an enzyme inhibitors do?

A

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

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3
Q

what are the two types of enzyme inhibitors?

A

irreversible inhibitors
reversible inhibitors

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4
Q

describe irreversible inhibitors

A

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

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5
Q

describe reversible inhibitors

A

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

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6
Q

can enzymes be drug products?

A

yes
e.g (streptokinase and tPA - clot busters)

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7
Q

what are statins also called?

A

HMG-CoA reductase inhibitors

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8
Q

what do statins do?

A

Block the rate limiting step in the Cholesterol pathway

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9
Q

what are statins classed as?

A

A class oflipid-lowering medications that reduces the levels of “bad cholesterol”

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10
Q

what are statins used for?

A

-For the primary prevention of cardiovascular disease
-Reducecardiovascular disease(CVD) and mortality in those who are at high risk.

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11
Q

name a major blood pressure regulating mechanism

A

Renin-angiotensin-aldosterone system

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12
Q

what does this RAAS system do?

A

The system increases blood pressure by increasing the amount of salt and water the body retains

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13
Q

what does inhibiting ACE do?

A

inhibiting ACE reduces angiotensin II production, which causes a reduction in blood pressure.

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14
Q

what are the symptoms of Parkinson’s disease?

A

-Hypokinesia – motor movement↓
-Tremor at rest
-Muscle rigidity, Motor inertia
-Cognitive impairment
Degenerative disease of basal ganglia
-Early degeneration of dopaminergic neurons in the nigrostriatial pathway leading to autonomic dysfunction and dementia

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15
Q

how is Parkinson’s treated?

A

with multiple enzymatic inhibitor drugs

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16
Q

what produces L-DOPA?

A

produced from the amino acid L-Tyrosine as a precursor for neurotransmitter biosynthesis - crosses the Blood Brain Barrier*

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17
Q

what is the blood brain barrier?

A

*BBB is a highly selective semi-permeable membrane barrier that separates the circulating blood from the brain

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18
Q

what does peripheral DDC inhibitor do?

A

Bocks DDC in the periphery generating more for the CNS pathway-
if you block this more L-DOPA transfers into the brain- less dopamine being produced
- has no effect outside of the brain

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19
Q

what does the peripheral COMT inhibitor do?

A

prevents breakdown of L-DOPA generating more for the CNS pathway

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20
Q

what does the central COMT inhibitor do?

A

Function within the CNS to keep Dopamine levels up

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21
Q

what do mono amine oxidase B inhibitors do?

A

Prevent Dopamine breakdown and increases availability

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22
Q

what do central dopamine receptor antagonists do?

A

Antagonise dopamine receptors (not enzyme inhibitors)

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23
Q

what are two ways drugs and ion are transported?

A

passive
active

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24
Q

examples of passive drug and ion transport methods

A

-Symporter (cotransporter protein) – NA/K/2Cl/NaCl
-Channels – Na/Ca/K/Cl
don’t require any energy

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25
Q

examples of active drug and ion transport methods

A

ATP-ases – Na/K, K/H
requires energy

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26
Q

define transport

A

when molecules move across a cell membrane

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27
Q

what is active transport

A

moves ions from a lower concentration to a higher concentration.

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28
Q

what does transport allow cells to get?

A

what they need such as ions, glucose, and amino acids. Transport needs energy, usually from ATP.

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29
Q

what are the three main type of protein ports in cell membranes?

A

uniporters
symporters
antiporters

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30
Q

describe uniporters

A

use energy from ATP to pull molecules in

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31
Q

describe symporters

A

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

32
Q

describe antiporters

A

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

33
Q

example of a symporter

A

NA-K-Cl co transporter

34
Q

what does the NKCC transporter do

A

Move ions in the same direction
Functions in organs that secrete fluids

35
Q

how does furosemide work?

A

a so-called loop diuretic - used for hypertensionandedema)
Acts by inhibiting the luminalNKCC in thethick ascending limbof theloop of Henle
Binding to the NKCC causes sodium, chloride, and potassium loss in urine

36
Q

examples of ion channels

A

epithelial (sodium) – heart failure
Voltage-gated (calcium, sodium) – nerve, arrhythmia
Metabolic (potassium) – diabetes
Receptor activated (chloride) – epilepsy

37
Q

what does heterotrimetic mean?

A

two set of three proteins

38
Q

describe ENAC

A

An (apical) membrane-bound heterotrimeric* ion channel selectively permeable to Na+ ions

39
Q

what does ENAC cause

A

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

40
Q

what is ENAC blocked by

A

the high affinity diuretic amiloride (often used with Thaizide).

41
Q

what does thiazide target?

A

Na+Cl− cotransporter that reabsorbs Na and Cl from tubular fluid
Used as a anti-hypertensive

42
Q

where are voltage gated ion channels found?

A

in the membrane of excitable cells (e.g., muscle, glial cells, neurons, etc.)

43
Q

when are voltage gated ion channels closed?

A

At physiologic or resting membrane potential,

44
Q

when are voltage gated ion channels open?

A

They are activated (i.e., opened) at depolarized membrane potentials (action potential)*.

45
Q

when ca2+ enters voltage gated ion channels what happens?

A

Ca2+ enters the cell, resulting in activation of Ca-sensitive K channels, muscular contraction, excitation of neurons etc.

46
Q

what is amlodipine?

A

angioselective

47
Q

why is amlodipine important?

A

Ca channel blocker that inhibits the movement of Ca ions into vascular smooth muscle cells and cardiac muscle cells

48
Q

what does amlodipine do?

A

This inhibits the contraction of cardiac muscle and vascular smooth muscle cells

Amlodipine inhibits Ca ion influx across cell membranes, with a greater effect on vascular smooth muscle cells
Also prevents excessive constriction in the coronary arteries

49
Q

what does amlodipine cause?

A

Causes vasodilation and a reduction peripheral vascular resistance, thus lowering blood pressure

50
Q

what do voltage gated sodium channels do

A

Conducts Na+ through plasma
membrane.

51
Q

how are voltage gated sodium channels classified

A

Classified according to the
trigger that opens them-
“Voltage-gated” or “ligand-
gated”.

52
Q

what are the three main confirmational states in excitable cells of voltage gated Na+ channels and K+ channels?

A

closed
open
inactivated

53
Q

when do voltage gated sodium channels open

A

An action potential allows the activation gates to open, allowing Na+ions to flow into the cell causing the voltage across the membrane to increase – transmits a signal

54
Q

what does lidocaine do

A

Lidocaine (anaesthetic) blocks transmission of the action potential. Also blocks signaling in the heart reducing arrhythmia.

55
Q

describe voltage gated potassium channels

A

Regulate insulin in Pancreas:  Islets of Langerhans
Increased glucose leads to block of ATP dependent K+ channels.
Repetitive firing of action potentials increases Ca+ influx and triggers insulin secretion
Repaglinide, nateglinide and sulfonylureal lower blood glucose levels by blocking K+ channels to stimulate insulin secretion.
Used for treatment of type II diabetes

56
Q

describe receptor mediated chloride channels?

A

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 is GABA -A Receptor

57
Q

what is the endogenous ligand inreceptor mediated chloride channels?

A

Endogenous ligand is γ-aminobutyric acid (GABA),the major inhibitory neurotransmitter in the CNS.

58
Q

what does GABA do

A

GABA A receptor is post-synaptic, opens Cl- channel - induces hyperpolarisation
Drugs can enhance activation of GABA A receptor by GABA
ie produce greater inhibition

59
Q

what do barbiturates do?

A

increase the permeability of the channel to chloride

60
Q

describe the Sodium Pump (Na/K ATP-ase)

A

Pumps Na out and K into cells, against their concentration gradients.
This pumping is active (energy comes from ATP).
It has antiporter-like activity (moves both molecules against their concentration gradients.
Pump 3 Na ions out for every 2 K ions in and creates a electrochemical gradient between a cell and its exterior.
The reverse process (unlike the forward) is spontaneous.

61
Q

what is digoxin used for

A

for atrial fibrillation, atrial flutter, and heart failure

62
Q

what does the digoxin do?

A

inhibition causes an increase in intracellular Na, resulting in decreased activity of the Na-Ca exchanger and increases intracellular Ca.

This lengthens the cardiac action potential, which leads to a decrease in heart rate.

63
Q

describe the proton pump (K/H ATP-ase) Stomach

A

The gastric hydrogen potassium ATPase or
H+/K+ ATPase is the proton pump of the stomach.

H+/K+ ATPase is a heterodimeric protein
(the product of 2 genes)

64
Q

what is the proton pump (K/H ATP-ase) Stomach responsible for ?

A

responsible for the acidification of the stomach and the activation of the digestive enzyme pepsin

65
Q

what is theproton pump (K/H ATP-ase) Stomach blocked by?

A

Proton-pump inhibitors (PPIs), they are the most potent inhibitors of acid secretion available

66
Q

what are organophosphates?

A

(Irreversible inhibitors of cholinesterase)

67
Q

examples of organophosphates

A

Insecticides (Diazinon)
- Nerve gases (Sarin)

68
Q

what are xenobiotics?

A

xenobiotics, are compounds foreign to an organism’s normal biochemistry, such any drug or poison.

69
Q

where does the metabolic breakdown of drugs occur?

A

through specialised enzymatic systems

70
Q

what does the rate of metabolism determine?

A

the duration and intensity of a drug’s pharmacologic action

71
Q

what Is pharmacokinetics

A

The study of drug metabolism

72
Q

how does drug metabolism work?

A

Works through biotransformation

73
Q

what does drug metabolism generate

A

Generates compounds that are (often inactivated and) more readily excreted (works in liver and kidney)

74
Q

what are the major enzymes involved in drug metabolism?

A

CYPs (e.g. cP450) are the major enzymes involved in drug metabolism (75%)
Most drugs undergo deactivation by CYPs, either directly or by facilitated excretion from the body.

75
Q
A

phase 2a (67 decks)

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