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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
examples of active drug and ion transport methods
ATP-ases – Na/K, K/H requires energy
26
define transport
when molecules move across a cell membrane
27
what is active transport
moves ions from a lower concentration to a higher concentration.
28
what does transport allow cells to get?
what they need such as ions, glucose, and amino acids. Transport needs energy, usually from ATP.
29
what are the three main type of protein ports in cell membranes?
uniporters symporters antiporters
30
describe uniporters
use energy from ATP to pull molecules in
31
describe symporters
use the movement in of one molecule to pull in another molecule against a concentration gradient
32
describe antiporters
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
example of a symporter
NA-K-Cl co transporter
34
what does the NKCC transporter do
Move ions in the same direction Functions in organs that secrete fluids
35
how does furosemide work?
a so-called loop diuretic - used for hypertension and edema) Acts by inhibiting the luminal NKCC  in the thick ascending limb of the loop of Henle Binding to the NKCC causes sodium, chloride, and potassium loss in urine
36
examples of ion channels
epithelial (sodium) – heart failure Voltage-gated (calcium, sodium) – nerve, arrhythmia Metabolic (potassium) – diabetes Receptor activated (chloride) – epilepsy
37
what does heterotrimetic mean?
two set of three proteins
38
describe ENAC
An (apical) membrane-bound heterotrimeric* ion channel selectively permeable to Na+ ions
39
what does ENAC cause
Causes reabsorption of Na+ ions at the collecting ducts of the kidney's nephrons (also in colon, lung and sweat glands)
40
what is ENAC blocked by
the high affinity diuretic amiloride (often used with Thaizide).
41
what does thiazide target?
Na+Cl− cotransporter that reabsorbs Na and Cl from tubular fluid Used as a anti-hypertensive
42
where are voltage gated ion channels found?
in the membrane of excitable cells (e.g., muscle, glial cells, neurons, etc.)
43
when are voltage gated ion channels closed?
At physiologic or resting membrane potential,
44
when are voltage gated ion channels open?
They are activated (i.e., opened) at depolarized membrane potentials (action potential)*.
45
when ca2+ enters voltage gated ion channels what happens?
Ca2+ enters the cell, resulting in activation of Ca-sensitive K channels, muscular contraction, excitation of neurons etc.
46
what is amlodipine?
angioselective
47
why is amlodipine important?
Ca channel blocker that inhibits the movement of Ca ions into vascular smooth muscle cells and cardiac muscle cells
48
what does amlodipine do?
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
what does amlodipine cause?
Causes vasodilation and a reduction peripheral vascular resistance, thus lowering blood pressure
50
what do voltage gated sodium channels do
Conducts Na+ through plasma membrane.
51
how are voltage gated sodium channels classified
Classified according to the trigger that opens them- “Voltage-gated” or “ligand- gated”.
52
what are the three main confirmational states in excitable cells of voltage gated Na+ channels and K+ channels?
closed open inactivated
53
when do voltage gated sodium channels open
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
what does lidocaine do
Lidocaine (anaesthetic) blocks transmission of the action potential. Also blocks signaling in the heart reducing arrhythmia.
55
describe voltage gated potassium channels
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
describe receptor mediated chloride channels?
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
what is the endogenous ligand inreceptor mediated chloride channels?
Endogenous ligand is γ-aminobutyric acid (GABA),the major inhibitory neurotransmitter in the CNS.
58
what does GABA do
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
what do barbiturates do?
increase the permeability of the channel to chloride
60
describe the Sodium Pump (Na/K ATP-ase)
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
what is digoxin used for
for atrial fibrillation, atrial flutter, and heart failure
62
what does the digoxin do?
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
describe the proton pump (K/H ATP-ase) Stomach
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
what is the proton pump (K/H ATP-ase) Stomach responsible for ?
responsible for the acidification of the stomach and the activation of the digestive enzyme pepsin
65
what is theproton pump (K/H ATP-ase) Stomach blocked by?
Proton-pump inhibitors (PPIs), they are the most potent inhibitors of acid secretion available
66
what are organophosphates?
(Irreversible inhibitors of cholinesterase)
67
examples of organophosphates
Insecticides (Diazinon) - Nerve gases (Sarin)
68
what are xenobiotics?
xenobiotics, are compounds foreign to an organism's normal biochemistry, such any drug or poison.
69
where does the metabolic breakdown of drugs occur?
through specialised enzymatic systems
70
what does the rate of metabolism determine?
the duration and intensity of a drug’s pharmacologic action
71
what Is pharmacokinetics
The study of drug metabolism
72
how does drug metabolism work?
Works through biotransformation
73
what does drug metabolism generate
Generates compounds that are (often inactivated and) more readily excreted (works in liver and kidney)
74
what are the major enzymes involved in drug metabolism?
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

phase 2a (67 decks)

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