Set 1
1. Define prodrug with example. What are the purposes of using prodrug?
* Definition: Prodrugs are chemical substances that do not produce pharmacological effects
until they are chemically altered within the body (converted to an active drug) .
* Examples: Enalapril, Levodopa, Omeprazole, Cyclophosphamide .
* Purposes:
* To facilitate absorption and distribution (e.g., Enalapril) .
* To promote site-specific delivery (e.g., Levodopa crossing the Blood-Brain Barrier) .
* To reduce adverse effects (e.g., Cyclophosphamide not damaging GIT mucosa) .
* To increase the duration of action of a drug that is rapidly eliminated .
* To overcome the problem of a patient's poor acceptance of a product .
2. What is the importance of plasma protein binding of a drug? Mention the consequences of
drug receptor interaction.
* Importance of Plasma Protein Binding:
* The bound fraction serves as a reservoir or storage depot .
* High binding decreases the volume of distribution .
* Bound drugs are devoid of biotransformation (metabolism) and excretion .
* They have a prolonged half-life .
* They are not removed by hemodialysis (e.g., large V drugs) .
* Drug interactions can occur via displacement (e.g., Warfarin, Phenytoin) .
* Consequences of Drug-Receptor Interaction:
* Agonist: The drug combines with the receptor and produces an effect (has affinity and
efficacy) .
* Antagonist: The drug combines with the receptor but produces no response (has affinity but
no efficacy) .
* Partial Agonist: The drug has affinity but low efficacy .
3. What is drug affinity? Differentiate between drug potency & efficacy.
* Affinity: The tendency of a drug to combine with a receptor to form a complex and maintain it .
,* Differentiation:
* Efficacy: The capacity of a drug to produce an effect . Drugs are chosen based on efficacy .
* Potency: The quantity of a drug required to achieve a desired effect; it is a comparative
measure between doses of two drugs .
4. Name the anticholinesterases. How do they act?
* Names:
* Reversible: Physostigmine, Neostigmine, Pyridostigmine, Rivastigmine, Gallantamine,
Donepezil, Edrophonium .
* Irreversible (Organophosphorous compounds): Ecothiophate, Malathion, Parathion, Sarin,
Soman, Tabun .
* Mechanism: They act by inhibiting the enzyme acetylcholinesterase (which breaks down
acetylcholine), thereby increasing the amount of acetylcholine available .
5. Define neurotransmitter. Enumerate the important criteria of an ideal neurotransmitter.
* Definition: A chemical substance released from a nerve ending that transmits an impulse from
nerve to nerve or nerve to effector organ .
* Criteria/Characteristics:
* Synthesis in the nerve ending .
* Storage in the nerve ending in vesicles .
* Release from the nerve ending .
* Function by binding with specific receptors (post-synaptic) .
* Termination of action in the nerve ending (synaptic cleft) .
Set 2
1. Name some drugs which are obtained from plants. Why now a day most of the drugs are
produced synthetically?
* Drugs from Plants: Atropine, Morphine, Quinine, Digoxin, Pilocarpine, Reserpine, Cocaine .
* Reason for Synthetic Production: Synthetic drugs are generally of high quality, less
expensive, can be produced on a large scale within a short time, and are often safer and more
effective .
2. Define drug absorption. Explain how PH of the gut influences drug absorption.
,* Definition: The passage of a drug from its site of administration into the blood through a
biological membrane .
* Influence of pH:
* Acidic Drugs: In an acidic environment (low pH), they retain H^+ and remain unionized,
making them more absorbed . In a basic environment, they become ionized and are less
absorbed .
* Basic Drugs: In a basic environment, they lose H^+ and remain unionized, making them
more absorbed . In an acidic environment, they become ionized and are less absorbed .
3. Explain with example how the action of a drug can be prolonged.
* By delaying absorption:
* Adding a 2nd drug (e.g., Adrenaline + Local Anesthetic) .
* Changing physical properties (e.g., Insulin + zinc suspension) .
* Esterification (e.g., Testosterone propionate) .
* By increasing plasma protein binding .
* By decreasing metabolism: Using enzyme inhibitors (e.g., Acetylcholinesterase inhibitors like
Neostigmine, or microsomal inhibitors like Cimetidine) .
* By decreasing excretion: e.g., Penicillin + Probenecid .
4. Name the reversible cholinesterases inhibitors. Mention the clinical uses of Neostigmine.
* Reversible Inhibitors: Physostigmine, Neostigmine, Pyridostigmine, Rivastigmine,
Gallantamine, Donepezil, Edrophonium .
* Clinical Uses of Neostigmine:
* Myasthenia gravis .
* Reversal of non-depolarizing neuromuscular blockade after surgery .
* Post-operative ileus & neurogenic bladder .
* Glaucoma .
5. Name the primary neurotransmitter of cholinergic & adrenergic system. Explain the role of
adrenaline in anaphylaxis.
* Primary Neurotransmitters:
* Cholinergic: Acetylcholine .
, * Adrenergic: Nor-adrenaline / Nor-epinephrine .
* Role of Adrenaline in Anaphylaxis (Physiological Antagonism):
* It stimulates \beta_2 receptors in bronchial smooth muscle causing bronchodilation
(counteracting histamine-induced constriction) .
* It stimulates \alpha_1 receptors in blood vessels causing vasoconstriction and increased
blood pressure (counteracting histamine-induced hypotension) .
* It stimulates \beta_1 receptors in the heart increasing force of contraction and cardiac
output .
Set 3
1. What is therapeutic index? Mention its clinical significance.
* Definition: It is the ratio of the median lethal dose (LD_{50}) or median toxic dose (TD_{50}) to
the median effective dose (ED_{50}). Formula: TI = TD_{50} / ED_{50} .
* Clinical Significance:
* It reflects the safety margin of a drug .
* A high therapeutic index indicates a safer drug (e.g., Penicillin, Paracetamol) .
* A low therapeutic index predicts a higher risk of toxicity (e.g., Digoxin, Warfarin) .
2. Define drug bioavaility. Name some important factors that influence it.
* Definition: The fraction of unchanged drug reaching the systemic circulation following
administration by any route .
* Factors Influencing It:
* Extent of Absorption: Solubility (lipid vs. water soluble) .
* First-Pass Metabolism: High first-pass metabolism reduces bioavailability .
* Rate of Absorption: Dependent on the route of administration (I/V is 100%) and drug
formulation (particle size, disintegration time) .
* Biological Factors: Destruction by gastric juice/enzymes, intestinal hurry, or binding with food
constituents .
3. Mention the different mechanisms of drug action. Explain how genetic factor modify drug
action.
* Mechanisms of Drug Action:
1. Define prodrug with example. What are the purposes of using prodrug?
* Definition: Prodrugs are chemical substances that do not produce pharmacological effects
until they are chemically altered within the body (converted to an active drug) .
* Examples: Enalapril, Levodopa, Omeprazole, Cyclophosphamide .
* Purposes:
* To facilitate absorption and distribution (e.g., Enalapril) .
* To promote site-specific delivery (e.g., Levodopa crossing the Blood-Brain Barrier) .
* To reduce adverse effects (e.g., Cyclophosphamide not damaging GIT mucosa) .
* To increase the duration of action of a drug that is rapidly eliminated .
* To overcome the problem of a patient's poor acceptance of a product .
2. What is the importance of plasma protein binding of a drug? Mention the consequences of
drug receptor interaction.
* Importance of Plasma Protein Binding:
* The bound fraction serves as a reservoir or storage depot .
* High binding decreases the volume of distribution .
* Bound drugs are devoid of biotransformation (metabolism) and excretion .
* They have a prolonged half-life .
* They are not removed by hemodialysis (e.g., large V drugs) .
* Drug interactions can occur via displacement (e.g., Warfarin, Phenytoin) .
* Consequences of Drug-Receptor Interaction:
* Agonist: The drug combines with the receptor and produces an effect (has affinity and
efficacy) .
* Antagonist: The drug combines with the receptor but produces no response (has affinity but
no efficacy) .
* Partial Agonist: The drug has affinity but low efficacy .
3. What is drug affinity? Differentiate between drug potency & efficacy.
* Affinity: The tendency of a drug to combine with a receptor to form a complex and maintain it .
,* Differentiation:
* Efficacy: The capacity of a drug to produce an effect . Drugs are chosen based on efficacy .
* Potency: The quantity of a drug required to achieve a desired effect; it is a comparative
measure between doses of two drugs .
4. Name the anticholinesterases. How do they act?
* Names:
* Reversible: Physostigmine, Neostigmine, Pyridostigmine, Rivastigmine, Gallantamine,
Donepezil, Edrophonium .
* Irreversible (Organophosphorous compounds): Ecothiophate, Malathion, Parathion, Sarin,
Soman, Tabun .
* Mechanism: They act by inhibiting the enzyme acetylcholinesterase (which breaks down
acetylcholine), thereby increasing the amount of acetylcholine available .
5. Define neurotransmitter. Enumerate the important criteria of an ideal neurotransmitter.
* Definition: A chemical substance released from a nerve ending that transmits an impulse from
nerve to nerve or nerve to effector organ .
* Criteria/Characteristics:
* Synthesis in the nerve ending .
* Storage in the nerve ending in vesicles .
* Release from the nerve ending .
* Function by binding with specific receptors (post-synaptic) .
* Termination of action in the nerve ending (synaptic cleft) .
Set 2
1. Name some drugs which are obtained from plants. Why now a day most of the drugs are
produced synthetically?
* Drugs from Plants: Atropine, Morphine, Quinine, Digoxin, Pilocarpine, Reserpine, Cocaine .
* Reason for Synthetic Production: Synthetic drugs are generally of high quality, less
expensive, can be produced on a large scale within a short time, and are often safer and more
effective .
2. Define drug absorption. Explain how PH of the gut influences drug absorption.
,* Definition: The passage of a drug from its site of administration into the blood through a
biological membrane .
* Influence of pH:
* Acidic Drugs: In an acidic environment (low pH), they retain H^+ and remain unionized,
making them more absorbed . In a basic environment, they become ionized and are less
absorbed .
* Basic Drugs: In a basic environment, they lose H^+ and remain unionized, making them
more absorbed . In an acidic environment, they become ionized and are less absorbed .
3. Explain with example how the action of a drug can be prolonged.
* By delaying absorption:
* Adding a 2nd drug (e.g., Adrenaline + Local Anesthetic) .
* Changing physical properties (e.g., Insulin + zinc suspension) .
* Esterification (e.g., Testosterone propionate) .
* By increasing plasma protein binding .
* By decreasing metabolism: Using enzyme inhibitors (e.g., Acetylcholinesterase inhibitors like
Neostigmine, or microsomal inhibitors like Cimetidine) .
* By decreasing excretion: e.g., Penicillin + Probenecid .
4. Name the reversible cholinesterases inhibitors. Mention the clinical uses of Neostigmine.
* Reversible Inhibitors: Physostigmine, Neostigmine, Pyridostigmine, Rivastigmine,
Gallantamine, Donepezil, Edrophonium .
* Clinical Uses of Neostigmine:
* Myasthenia gravis .
* Reversal of non-depolarizing neuromuscular blockade after surgery .
* Post-operative ileus & neurogenic bladder .
* Glaucoma .
5. Name the primary neurotransmitter of cholinergic & adrenergic system. Explain the role of
adrenaline in anaphylaxis.
* Primary Neurotransmitters:
* Cholinergic: Acetylcholine .
, * Adrenergic: Nor-adrenaline / Nor-epinephrine .
* Role of Adrenaline in Anaphylaxis (Physiological Antagonism):
* It stimulates \beta_2 receptors in bronchial smooth muscle causing bronchodilation
(counteracting histamine-induced constriction) .
* It stimulates \alpha_1 receptors in blood vessels causing vasoconstriction and increased
blood pressure (counteracting histamine-induced hypotension) .
* It stimulates \beta_1 receptors in the heart increasing force of contraction and cardiac
output .
Set 3
1. What is therapeutic index? Mention its clinical significance.
* Definition: It is the ratio of the median lethal dose (LD_{50}) or median toxic dose (TD_{50}) to
the median effective dose (ED_{50}). Formula: TI = TD_{50} / ED_{50} .
* Clinical Significance:
* It reflects the safety margin of a drug .
* A high therapeutic index indicates a safer drug (e.g., Penicillin, Paracetamol) .
* A low therapeutic index predicts a higher risk of toxicity (e.g., Digoxin, Warfarin) .
2. Define drug bioavaility. Name some important factors that influence it.
* Definition: The fraction of unchanged drug reaching the systemic circulation following
administration by any route .
* Factors Influencing It:
* Extent of Absorption: Solubility (lipid vs. water soluble) .
* First-Pass Metabolism: High first-pass metabolism reduces bioavailability .
* Rate of Absorption: Dependent on the route of administration (I/V is 100%) and drug
formulation (particle size, disintegration time) .
* Biological Factors: Destruction by gastric juice/enzymes, intestinal hurry, or binding with food
constituents .
3. Mention the different mechanisms of drug action. Explain how genetic factor modify drug
action.
* Mechanisms of Drug Action:
