UNIVERSITY OF SOUTH AFRICA (UNISA)
Department of Life and Consumer Sciences
⋄
BMI2605 ASSIGNMENT 02
Pharmacology – Semester 1, 2026
⋄
Module Code: BMI2605
Module Name: Pharmacology
Student Name: [Your Full Name]
Student Number: [Your Student Number]
Assignment No.: 02
Due Date: 21 April 2026
Semester: Semester 1, 2026
Unique Number: 257221
Submitted in partial fulfilment of the requirements for BMI2605
at the University of South Africa.
,UNISA | BMI2605 Pharmacology – Assignment 02
Contents
1 Question 1: Core Pharmacological Concepts 3
1.1 1.1 The Therapeutic Index and Its Significance in Pharmacology . . . . . . . . . 3
1.2 1.2 Potency Versus Efficacy in Drug Action . . . . . . . . . . . . . . . . . . . . . 4
1.3 1.3 First-Pass Metabolism and Its Effect on Oral Drug Administration . . . . . . 4
1.4 1.4 Pharmacokinetics Versus Pharmacodynamics . . . . . . . . . . . . . . . . . 5
1.5 1.5 Selective Toxicity and a Clinical Example . . . . . . . . . . . . . . . . . . . . . 6
2 Question 2: AUC, Bioavailability, and Receptor Pharmacology 7
2.1 2.1 The Area Under the Curve (AUC): Drug Exposure and Bioavailability . . . . . 7
2.2 2.2 Full Agonists, Partial Agonists, and Antagonists . . . . . . . . . . . . . . . . 8
2.2.1 Full Agonists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2.2 Partial Agonists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2.3 Antagonists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3 Question 3: Drug Metabolism, CYP450, and Drug-Receptor Interaction 10
3.1 3.1 Cytochrome P450 Enzymes in Drug Metabolism and Drug Interaction Conse-
quences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.2 3.2 The Two Phases of Drug Metabolism . . . . . . . . . . . . . . . . . . . . . . . 11
3.2.1 Phase I Metabolism: Functionalisation Reactions . . . . . . . . . . . . . . 11
3.2.2 Phase II Metabolism: Conjugation Reactions . . . . . . . . . . . . . . . . . 12
3.3 3.3 The Drug-Receptor Interaction Concept and Its Significance . . . . . . . . . 13
4 Question 4: Hypertension – Lifestyle Factors and ACE Inhibitor Pharmacology 14
4.1 4.1 Lifestyle Factors Associated with Hypertension . . . . . . . . . . . . . . . . . 14
4.2 4.2 ACE Inhibitors: Mechanism of Action and Therapeutic Use in Hypertension . 15
Page 1 of 18
,UNISA | BMI2605 Pharmacology – Assignment 02
4.2.1 The Renin-Angiotensin-Aldosterone System (RAAS) . . . . . . . . . . . . . 16
4.2.2 Mechanism of Action of ACE Inhibitors . . . . . . . . . . . . . . . . . . . . 16
4.2.3 Therapeutic Uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Reference List 18
Page 2 of 18
, UNISA | BMI2605 Pharmacology – Assignment 02
Question 1: Core Pharmacological Concepts
1.1 The Therapeutic Index and Its Significance in Pharmacology
The therapeutic index (TI) is a quantitative measure that expresses the relationship between
the dose of a drug that produces a therapeutic effect and the dose that produces a toxic or
lethal effect in a population (Brunton et al., 2018). It is calculated as:
TD50
TI =
ED50
where TD50 is the dose that produces toxicity in 50% of the population and ED50 is the dose
that produces the desired therapeutic effect in 50% of the population. In animal studies, LD50
(lethal dose in 50%) is sometimes used in place of TD50 (Katzung et al., 2021).
Significance. A high therapeutic index means there is a wide margin between the effective
dose and the toxic dose, so the drug can be used safely across a broad range of patient weights,
ages, and metabolic capacities. Penicillin, for example, has a very high TI; accidental over-
dose rarely causes serious toxicity. In contrast, drugs with a narrow therapeutic index, such
as warfarin, digoxin, lithium, and aminoglycoside antibiotics, require careful dose monitoring
because the toxic dose is only slightly above the therapeutic dose (Rang et al., 2020). Even
modest changes in a patient’s renal function, protein binding, or drug interactions can push a
narrow-TI drug into the toxic range. In clinical practice, narrow-TI drugs typically require ther-
apeutic drug monitoring (blood level measurement) to maintain the patient within the thera-
peutic window. The TI therefore directly informs prescribing decisions, monitoring protocols,
and the design of drug delivery systems (Brunton et al., 2018).
Critical Consideration
Critical Consideration: The therapeutic index is a population statistic, not an individual
guarantee. A drug with a TI of 10 still carries risk in individual patients who metabolise
it unusually slowly (e.g., due to genetic polymorphisms in CYP enzymes) or who have
renal or hepatic impairment affecting drug clearance (Katzung et al., 2021).
Page 3 of 18
Department of Life and Consumer Sciences
⋄
BMI2605 ASSIGNMENT 02
Pharmacology – Semester 1, 2026
⋄
Module Code: BMI2605
Module Name: Pharmacology
Student Name: [Your Full Name]
Student Number: [Your Student Number]
Assignment No.: 02
Due Date: 21 April 2026
Semester: Semester 1, 2026
Unique Number: 257221
Submitted in partial fulfilment of the requirements for BMI2605
at the University of South Africa.
,UNISA | BMI2605 Pharmacology – Assignment 02
Contents
1 Question 1: Core Pharmacological Concepts 3
1.1 1.1 The Therapeutic Index and Its Significance in Pharmacology . . . . . . . . . 3
1.2 1.2 Potency Versus Efficacy in Drug Action . . . . . . . . . . . . . . . . . . . . . 4
1.3 1.3 First-Pass Metabolism and Its Effect on Oral Drug Administration . . . . . . 4
1.4 1.4 Pharmacokinetics Versus Pharmacodynamics . . . . . . . . . . . . . . . . . 5
1.5 1.5 Selective Toxicity and a Clinical Example . . . . . . . . . . . . . . . . . . . . . 6
2 Question 2: AUC, Bioavailability, and Receptor Pharmacology 7
2.1 2.1 The Area Under the Curve (AUC): Drug Exposure and Bioavailability . . . . . 7
2.2 2.2 Full Agonists, Partial Agonists, and Antagonists . . . . . . . . . . . . . . . . 8
2.2.1 Full Agonists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2.2 Partial Agonists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2.3 Antagonists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3 Question 3: Drug Metabolism, CYP450, and Drug-Receptor Interaction 10
3.1 3.1 Cytochrome P450 Enzymes in Drug Metabolism and Drug Interaction Conse-
quences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.2 3.2 The Two Phases of Drug Metabolism . . . . . . . . . . . . . . . . . . . . . . . 11
3.2.1 Phase I Metabolism: Functionalisation Reactions . . . . . . . . . . . . . . 11
3.2.2 Phase II Metabolism: Conjugation Reactions . . . . . . . . . . . . . . . . . 12
3.3 3.3 The Drug-Receptor Interaction Concept and Its Significance . . . . . . . . . 13
4 Question 4: Hypertension – Lifestyle Factors and ACE Inhibitor Pharmacology 14
4.1 4.1 Lifestyle Factors Associated with Hypertension . . . . . . . . . . . . . . . . . 14
4.2 4.2 ACE Inhibitors: Mechanism of Action and Therapeutic Use in Hypertension . 15
Page 1 of 18
,UNISA | BMI2605 Pharmacology – Assignment 02
4.2.1 The Renin-Angiotensin-Aldosterone System (RAAS) . . . . . . . . . . . . . 16
4.2.2 Mechanism of Action of ACE Inhibitors . . . . . . . . . . . . . . . . . . . . 16
4.2.3 Therapeutic Uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Reference List 18
Page 2 of 18
, UNISA | BMI2605 Pharmacology – Assignment 02
Question 1: Core Pharmacological Concepts
1.1 The Therapeutic Index and Its Significance in Pharmacology
The therapeutic index (TI) is a quantitative measure that expresses the relationship between
the dose of a drug that produces a therapeutic effect and the dose that produces a toxic or
lethal effect in a population (Brunton et al., 2018). It is calculated as:
TD50
TI =
ED50
where TD50 is the dose that produces toxicity in 50% of the population and ED50 is the dose
that produces the desired therapeutic effect in 50% of the population. In animal studies, LD50
(lethal dose in 50%) is sometimes used in place of TD50 (Katzung et al., 2021).
Significance. A high therapeutic index means there is a wide margin between the effective
dose and the toxic dose, so the drug can be used safely across a broad range of patient weights,
ages, and metabolic capacities. Penicillin, for example, has a very high TI; accidental over-
dose rarely causes serious toxicity. In contrast, drugs with a narrow therapeutic index, such
as warfarin, digoxin, lithium, and aminoglycoside antibiotics, require careful dose monitoring
because the toxic dose is only slightly above the therapeutic dose (Rang et al., 2020). Even
modest changes in a patient’s renal function, protein binding, or drug interactions can push a
narrow-TI drug into the toxic range. In clinical practice, narrow-TI drugs typically require ther-
apeutic drug monitoring (blood level measurement) to maintain the patient within the thera-
peutic window. The TI therefore directly informs prescribing decisions, monitoring protocols,
and the design of drug delivery systems (Brunton et al., 2018).
Critical Consideration
Critical Consideration: The therapeutic index is a population statistic, not an individual
guarantee. A drug with a TI of 10 still carries risk in individual patients who metabolise
it unusually slowly (e.g., due to genetic polymorphisms in CYP enzymes) or who have
renal or hepatic impairment affecting drug clearance (Katzung et al., 2021).
Page 3 of 18
