Why was terfenadine withdrawn from the market?

Terfenadine was withdrawn because it could cause dangerous QT prolongation and life-threatening cardiac arrhythmias, especially when its metabolism was inhibited.

Which drugs require therapeutic drug monitoring?

Drugs with narrow therapeutic ranges or variable pharmacokinetics, such as digoxin, phenytoin, lithium, aminoglycosides, and some anticonvulsants, are common candidates.

What pharmacokinetic parameter is used to calculate a digoxin loading dose?

The loading dose is primarily estimated using the drug’s volume of distribution, along with the target concentration and bioavailability.

Free Course Image Introduction to Clinical Pharmacology and Therapeutics

Free online course Introduction to Clinical Pharmacology and Therapeutics

Duration of the online course: 1 hours and 22 minutes

4.9

(16)

Build safer prescribing skills with a free online clinical pharmacology course—master dosing, monitoring, interactions, and therapeutic decision-making.

In this free course, learn about

Scope and aims of clinical pharmacology and therapeutics
Who founded the journal Clinical Pharmacology and Therapeutics (1960)
Why terfenadine was withdrawn (serious cardiac arrhythmias/QT prolongation)
Definition and purpose of drug repurposing
Which drugs are appropriate candidates for therapeutic drug monitoring (TDM)
Loading dose estimation using key PK parameter: volume of distribution (e.g., digoxin)
Calculate daily digoxin loss from total body stores using fractional loss
Creatinine clearance estimation with the Cockcroft–Gault equation (since the 1970s)
Why phenytoin urine metabolite stays constant despite falling plasma levels (saturable metabolism)

About the free online course

Clinical pharmacology sits at the point where science becomes safe, effective patient care. This free online course is designed to help you strengthen the judgment needed to choose the right medicine, at the right dose, for the right person—especially when real-world variables like kidney function, variability in response, and safety concerns complicate decisions.

Through clear explanations and practice questions, you will connect core principles of pharmacokinetics and therapeutics to everyday clinical thinking. You will learn how dosing decisions are grounded in measurable parameters, how loading and maintenance doses are estimated, and why therapeutic drug monitoring can be essential for medicines with narrow therapeutic windows. You will also explore how changes in clearance and metabolism can alter exposure over time, shaping both effectiveness and adverse effects.

The course uses real historical and clinical examples to show how evidence, regulation, and patient safety influence prescribing. You will reflect on why certain drugs have been withdrawn, how unexpected risks can emerge after widespread use, and what modern approaches like drug repurposing mean for finding new treatments. You will also practice reasoning with common clinical calculations, including renal function estimation and interpreting patterns in metabolite excretion that can seem counterintuitive at first.

By the end, you should feel more confident linking drug concentrations to outcomes, recognizing when monitoring is appropriate, and asking the right questions when a patient is not responding as expected. Whether you are a health student, a clinician refreshing fundamentals, or a curious learner exploring pharmacology, this course offers a practical foundation for safer, smarter therapeutic decisions.

Course content

Video class: Introduction to Clinical Pharmacology and Therapeutics with Dr. Juan J.L. Lertora 1h22m
Exercise: Who founded the journal Clinical Pharmacology and Therapeutics in 1960?
Exercise: What was the reason for the withdrawal of terphenidine from the market?
Exercise: What is drug repurposing?
Exercise: What drugs are candidates for therapeutic drug monitoring?
Exercise: What is the primary pharmacokinetic parameter used to estimate the loading dose of drugs like digoxin?
Exercise: What is the daily loss of digoxin in an individual with a total body store of 0.75 milligrams if one-third of the total body stores of digoxin is lost daily?
Exercise: Which equation has been in use since the 1970s to estimate the clearance of creatinine?
Exercise: What is the reason for the constant amount of the parahydroxyl metabolite of phenytoin in the urine despite the falling plasma concentrations of the drug over time?