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Pharmacology > Pharmacodynamics: MECHANISMS OF DRUG ACTION > Flashcards

Pharmacodynamics: MECHANISMS OF DRUG ACTION Flashcards

1
Q

Pharmacodynamics is derived from two Greek words:

A

PHARMAKON-Drug
DYNAMIKOS- force or power

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2
Q

Pharmacodynamics is defined as the study of:

A

• Defined as the study of action of drugs- effects of drugs and dose-effect relationship.
It describes what a drug does to the body.
• It is modification of action of one drug by another drug.

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3
Q

Pharmacodynamics involves:

A

Receptor binding(including receptor sensitivity)
Post-receptor effects
Chemical interactions

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4
Q

Pharmacodynamics is the study of biochemical and physiological effects of drug and their mechanism of action at_____ level as well as ____ level.

A

Organ, cellular

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5
Q

The STRENGTH and LENGTH of interaction of drugs with a biological structure(eg 3 examples) determines HOW QUICKLY THE DRUG INITIATES THE EFFECT AND HOW LONG THE EFFECT LASTS.
True/False

A

Receptor
Enzyme
Transporter

TRUE

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6
Q

Penicillin molecule binds to bacterial enzyme, ______ and prevents ___ in the bacterial cell wall.

A

TRANSPEPTIDASE.
Cross links

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7
Q

Large amounts of penicillin completely blocks the enzyme and in the presence of small amounts, the enzyme resumes its normal function.
True/False

A

TRUE
This shows that the interaction between penicillin and the enzymes depends on the amount of penicillin present.

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8
Q

Factors such as:
Aging
Effects of other drugs
Disorders which can change receptor binding; decreasing receptor sensitivity or altering the level of binding proteins CANNOT affect a drug’s pharmacodynamics.
True/False

A

False . It can affect the drug’s pharmacodynamics.

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9
Q

Examples of disorders which cause change in receptor binding:

A

Genetic mutations
Malnutrition
Thyrotoxicosis

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10
Q

Concerning principles of drug action,
Drugs impart new functions on system, organ or cell and also alters the pace of ongoing activity.
True/False.

A

FALSE. Drugs DON’T impart new functions on any system, organ or cell but rather alters PACE of ongoing activity!
An exception to this are GENE-BASED DRUGS

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11
Q

Basic types of drug action can be broadly grouped as:

A

STIMULATION
DEPRESSION
IRRITATION
REPLACEMENT
CYTOTOXIC ACTION

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12
Q

______ is the SELECTIVE enhancement of the level of activity of specialized cells.

A

STIMULATION

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13
Q

Examples of stimulation:

A

PILOCARPINE on salivary glands
ADRENALINE on the heart

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14
Q

Define DEPRESSION:

A

It is the SELECTIVE diminution of activity of specialized cells.

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15
Q

Examples of DEPRESSION:

A

Barbiturates on the CNS
Quinidine on the heart
Omeprazole on gastric secretion

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16
Q

IRRITATION is applied to _____ cells (epithelium and Connective tissue). It results in a _____ and often noxious effect. Strong irritation results in inflammation, _____,_____ and consequently, _____

A

Non-specialized
Non-selective
Corrosion, Necrosis
Loss of function

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17
Q

Examples of Irritation:

A

Bitters in salivary and gastric secretion

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18
Q

______ the use of NATURAL METABOLITES, hormones or their congeners in deficiency states.

A

REPLACEMENT

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19
Q

Examples of replacement:

A

Levodopa in Parkinson’s disease (levodopa is a precursor to dopamine)
Insulin in Diabetes Milletus

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20
Q

Cytotoxic action involves selective cytotoxic action on cancer cells or invading organisms, attenuating them without significantly affecting the host cells.
True/False

A

True

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21
Q

Examples of cytotoxic action:

A

Cyclophosphamide - chemotherapy drug
Zidovudine- antiretroviral drug
Penicillin- antibiotics

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22
Q

Mechanism of Drug Action:

A

Physical mechanism
Chemical mechanism

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23
Q

__________ is when the drug does not produce any chemical reaction or change in the cells of the body and the effect is only physical. Examples are:

A

Physical mechanism
Activated charcoal binds with poisons in the stomach
Mannitol as an osmotic diuretic( freely filtered but not reabsorbed)
Bulk laxatives eg Ispaghula

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24
Q

Drugs that act by producing chemical reactions in the body uses _______ mechanism.

A

Chemical Mechanism

25
Q

Examples of chemical mechanisms:

A

•NAHCO3 as antacid
•Dimercaprol, penicillamine, desferrioxamine as chelating agents
•Pralidoxime as a choline esterase reactivator
•Cholestyramine for sequestration of bile acids and cholesterol in the gut

26
Q

Examples of discrete target bio-molecule drugs interact with:

A

Enzymes
Carrier molecules
Ion channels
Receptor

27
Q

Drug- enzyme interactions may take place as _______ or _______

A

Enzyme inactivation
Enzyme inhibition

28
Q

Enzyme inhibition may either be:

A

Competitive inhibition
Non-competitive inhibition

29
Q

ACE inhibitors eg captopril
Reversible anticholinesterases eg neostigmine, physostigmine
Allopurinol used to inhibit xanthine oxidase in gout are examples of NON-COMPETITVE INHIBITION.
True/False

A

FALSE. They are examples of competitive inhibition

30
Q

Neostigmine and Physostigmine are referred to as:

A

REVERSIBLE CHOLINESTERASE INHIBITORS

31
Q

Mechanism of allopurinol?

A

Allopurinol prevents gout-inflammation due to build up of urate crystals in joints by inhibition of xanthine oxidase which coverts xanthine and hypoxanthine uric acid.

32
Q

In non-competitive inhibition, effects are prolonged. True/False

A

True

33
Q

Examples of non-competitive inhibition:

A

Irreversible anticholinesterases eg organophosphorus compounds- insecticides and war gases
Aspirin inhibits cyclooxygenase enzyme and therefore prostaglandin synthesis
MAO inhibitors uses to treat depression eg Imipramine
(NB: Depression is associated with decrease in catecholamines eg adrenaline. Monoamine oxidase helps with degradation of catecholamines so a MAO inhibitor helps to inhibit the effect of MAO therefore can be used to treat depression).
Proton pump inhibitors: omeprazole inhibiting H+/K+ ATPase in parietal cells of stomach

34
Q

Some drugs intefere with the flow of Ion through the channels. Some of the ions are:

A

Na+
K+
Ca2+
Cl-

35
Q

Sodium channel drugs are:
They help in treatment of?

A

Quinidine- anti-arrhythmic drug
Procainamide- anti-arrhythmic drug
Local anesthetics

Cardiac arrhythmias and as local anesthetic

36
Q

Calcium channel drugs:
Useful in what conditions:

A

Nifedipine(hypertension and angina)
Verapamil (angina, hypertension, tachycardia)
Diltiazem(angina, hypertension,arrhythmia)

Hypertension
Arrhythmias

37
Q

Potassium channel drugs:

A

Amiodarone, Sulfonylureas

Amiodarone used in treating arrhythmias

38
Q

Chloride channel drugs:
Affect what receptor:

A

Benzodiazepines
GABA A receptor

39
Q

Inhibition of choline carrier by ______

A

Hemicholium

40
Q

Inhibition of noradrenaline vesicular uptake by _____

A

Reserpine

41
Q

Inhibition of neuronal uptake of noradrenaline ______

A

Desipramine

42
Q

Inhibition of neuronal uptake of serotonin _____

A

Fluoxetine aka PROZAC

43
Q

Inhibition of weak acid(eg uric acid) carrier by drugs _______

A

Probenecid which prevents uric acid tubular reabsorption thus enhancing its excretion

44
Q

_______ are regulatory macromolecular proteins.

A

Drug receptors

45
Q

_______ is an agent which activates a receptor to produce an effect similar to the physiological signal molecule. Example:

A

AGONIST
Acetylcholine
Noradrenaline
Adrenaline

46
Q

______ are agents which prevents the action of an agonist on a receptor but does not have any effect of its own. Example:

A

Antagonist
Atropine ( competitive antagonist of acetylcholine)
Scopalamine(antimuscarinic)
Phenoxybenzamine(non- competitive antagonist of noradrenaline)

47
Q

_____ is an agent which activates a receptor to produce submaximal effect, but antagonizes the effect of a fill agonist.

A

Partial agonist

48
Q

_____ is an agent which activates a receptor to produce an effect in the opposite direction of that of the agonist. Example:

A

INVERSE AGONIST

Beta carbolines

49
Q

What is a ligand?
Give examples

A

A ligand is any molecule which attaches selectively to particular receptors or sites.

Ach, Noradrenaline, adrenaline, glutamate, aspartate and GABA

50
Q

Affinity is defined as the ____ by which a ligand binds to its receptor.

A

Tenacity

51
Q

Some drugs possess affinity but NOT efficacy. True/False

A

True

52
Q

The capacity to induce functional change in the receptor in a way that produces an effect is ______

A

Intrinsic Activity

53
Q

For agonist:
Affinity + IA = ?

A

1

54
Q

For Antagonist:
Affinity + IA = ?

A

0

55
Q

For Partial Agonist:
Affinity + IA = ?

A

Between 0 and 1

56
Q

For Inverse agonist:
Affinity + IA = ?

A

Between 0 and -1

57
Q

Two essential functions of receptor:

A

Recognition of specific ligand molecule
Transduction of signal into response

58
Q

Receptors have two domains, namely:

A

Ligand binding domain
Effectors domain(undergoes conformational change)

Pharmacology (6 decks)

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