UNIVERSITY OF SOUTH AFRICA
Department of Life and Consumer Sciences
⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄⋄
BMI2605: Pharmacology
Assignment 02 — First Semester, 2026
⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄⋄
BMI2605
Module Code:
Pharmacology
Module Name:
02
Assignment Number:
257221
Unique Number:
01
Semester Code:
21 April 2026
Due Date:
100
Total Marks:
Submitted in partial fulfilment of the require-
ments for Pharmacology (BMI2605) — UNISA 2026
,UNISA | BMI2605 Pharmacology – Assignment 02
Contents
1 Question 1: Foundational Pharmacological Concepts 3
1.1 1.1 The Therapeutic Index and Its Significance . . . . . . . . . . . . . . . . . . . 3
1.2 1.2 Potency versus Efficacy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3 1.3 First-Pass Metabolism and Oral Drug Administration . . . . . . . . . . . . . . 4
1.4 1.4 Pharmacokinetics versus Pharmacodynamics . . . . . . . . . . . . . . . . . . 5
1.5 1.5 Selective Toxicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 Question 2: Drug Exposure and Receptor Pharmacology 7
2.1 2.1 The Area Under the Curve (AUC) in Pharmacokinetics . . . . . . . . . . . . . 7
2.2 2.2 Full Agonists, Partial Agonists, and Antagonists . . . . . . . . . . . . . . . . 8
2.2.1 Full Agonists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2.2 Partial Agonists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2.3 Antagonists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3 Question 3: Drug Metabolism 10
3.1 3.1 Cytochrome P450 Enzymes and Drug Interactions . . . . . . . . . . . . . . . 10
3.2 3.2 The Two Phases of Drug Metabolism . . . . . . . . . . . . . . . . . . . . . . . 11
3.2.1 Phase I Metabolism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.2.2 Phase II Metabolism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.3 3.3 The Drug-Receptor Interaction Concept . . . . . . . . . . . . . . . . . . . . . 13
4 Question 4: Hypertension – Lifestyle and Pharmacotherapy 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
Reference List 17
Page 2 of 18
, UNISA | BMI2605 Pharmacology – Assignment 02
Question 1: Foundational Pharmacological Concepts
Pharmacology rests on a set of foundational concepts that guide how drugs are developed,
dosed, and used in clinical practice (Katzung, Masters and Trevor, 2012). Each concept below
addresses a distinct but related aspect of drug action and safety.
1.1 The Therapeutic Index and Its Significance
The therapeutic index (TI) is a ratio that compares the dose at which a drug produces toxic
effects in 50% of a study population (TD50 ) to the dose that achieves the desired therapeu-
tic effect in 50% of that same population (ED50 ), expressed as TI = TD50 / ED50 (Muller and
Milton, 2012). Expressed differently, a larger TI signals a wide gap between benefit and harm,
while a small TI means those two thresholds sit uncomfortably close together.
The TI matters in practice because it tells clinicians how much room they have to work with.
Drugs with a wide TI, such as penicillin, can be prescribed at doses well above the minimum
effective concentration without serious risk. Narrow TI drugs, such as warfarin, digoxin,
lithium, and theophylline, are far less forgiving. A small dosage error or a shift in the patient’s
metabolism can push concentrations from therapeutic into toxic territory (Tamargo et al.,
2015). This is why narrow TI drugs require therapeutic drug monitoring (TDM), where blood
concentrations are checked routinely and doses adjusted accordingly.
Critical Consideration
TI has real limits. LD50 data are often derived from animal studies and may not map
cleanly onto human toxicity. Inter-individual differences in metabolism, body weight,
age, and comorbidities mean that the TI calculated from population-level data may not
apply to every patient (Muller and Milton, 2012). Always use the TI as a starting point,
not a guarantee.
1.2 Potency versus Efficacy
These two terms get confused constantly, yet they describe entirely different properties of a
drug.
Potency is about dose. A drug is said to be potent when a small amount of it produces a
given effect. Technically, potency refers to the concentration (or dose) required to produce
Page 3 of 18
Department of Life and Consumer Sciences
⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄⋄
BMI2605: Pharmacology
Assignment 02 — First Semester, 2026
⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄⋄
BMI2605
Module Code:
Pharmacology
Module Name:
02
Assignment Number:
257221
Unique Number:
01
Semester Code:
21 April 2026
Due Date:
100
Total Marks:
Submitted in partial fulfilment of the require-
ments for Pharmacology (BMI2605) — UNISA 2026
,UNISA | BMI2605 Pharmacology – Assignment 02
Contents
1 Question 1: Foundational Pharmacological Concepts 3
1.1 1.1 The Therapeutic Index and Its Significance . . . . . . . . . . . . . . . . . . . 3
1.2 1.2 Potency versus Efficacy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3 1.3 First-Pass Metabolism and Oral Drug Administration . . . . . . . . . . . . . . 4
1.4 1.4 Pharmacokinetics versus Pharmacodynamics . . . . . . . . . . . . . . . . . . 5
1.5 1.5 Selective Toxicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 Question 2: Drug Exposure and Receptor Pharmacology 7
2.1 2.1 The Area Under the Curve (AUC) in Pharmacokinetics . . . . . . . . . . . . . 7
2.2 2.2 Full Agonists, Partial Agonists, and Antagonists . . . . . . . . . . . . . . . . 8
2.2.1 Full Agonists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2.2 Partial Agonists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2.3 Antagonists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3 Question 3: Drug Metabolism 10
3.1 3.1 Cytochrome P450 Enzymes and Drug Interactions . . . . . . . . . . . . . . . 10
3.2 3.2 The Two Phases of Drug Metabolism . . . . . . . . . . . . . . . . . . . . . . . 11
3.2.1 Phase I Metabolism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.2.2 Phase II Metabolism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.3 3.3 The Drug-Receptor Interaction Concept . . . . . . . . . . . . . . . . . . . . . 13
4 Question 4: Hypertension – Lifestyle and Pharmacotherapy 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
Reference List 17
Page 2 of 18
, UNISA | BMI2605 Pharmacology – Assignment 02
Question 1: Foundational Pharmacological Concepts
Pharmacology rests on a set of foundational concepts that guide how drugs are developed,
dosed, and used in clinical practice (Katzung, Masters and Trevor, 2012). Each concept below
addresses a distinct but related aspect of drug action and safety.
1.1 The Therapeutic Index and Its Significance
The therapeutic index (TI) is a ratio that compares the dose at which a drug produces toxic
effects in 50% of a study population (TD50 ) to the dose that achieves the desired therapeu-
tic effect in 50% of that same population (ED50 ), expressed as TI = TD50 / ED50 (Muller and
Milton, 2012). Expressed differently, a larger TI signals a wide gap between benefit and harm,
while a small TI means those two thresholds sit uncomfortably close together.
The TI matters in practice because it tells clinicians how much room they have to work with.
Drugs with a wide TI, such as penicillin, can be prescribed at doses well above the minimum
effective concentration without serious risk. Narrow TI drugs, such as warfarin, digoxin,
lithium, and theophylline, are far less forgiving. A small dosage error or a shift in the patient’s
metabolism can push concentrations from therapeutic into toxic territory (Tamargo et al.,
2015). This is why narrow TI drugs require therapeutic drug monitoring (TDM), where blood
concentrations are checked routinely and doses adjusted accordingly.
Critical Consideration
TI has real limits. LD50 data are often derived from animal studies and may not map
cleanly onto human toxicity. Inter-individual differences in metabolism, body weight,
age, and comorbidities mean that the TI calculated from population-level data may not
apply to every patient (Muller and Milton, 2012). Always use the TI as a starting point,
not a guarantee.
1.2 Potency versus Efficacy
These two terms get confused constantly, yet they describe entirely different properties of a
drug.
Potency is about dose. A drug is said to be potent when a small amount of it produces a
given effect. Technically, potency refers to the concentration (or dose) required to produce
Page 3 of 18
