What is The Role of Pharmacokinetics in Genetic Testing in South Africa?

Written by: 
Jeanne Conradie

To understand how genetic testing in South Africa works one must first understand the role pharmacogenetics plays in people’s lives. This article will give you a brief description of drug metabolisation in terms of the pharmacokinetics and pharmacodynamics and how genetic labs in South Africa can use your genetic makeup to better describe how your body will likely handle certain prescription medication.

What is Pharmacodynamics?

Pharmacodynamics is the effect that different drugs have on the body. This is why it is closely related to clinical pharmacology.

What is Pharmacokinetics?

Pharmacokinetics is the study of the way drugs move through the body or what your body does to metabolise the drug. Another way to think of it is that pharmacodynamics is the end result of the process studied in pharmacokinetics.

For this article we will focus on the pharmacokinetic process of drugs administered orally. Drugs administered orally are absorbed in the stomach and the small intestine, and are strongly dependent on the pH and food interaction (hence why it is important to take a drug either before meals or directly after meals).

When drugs which are injected into the muscle, absorption takes place in the subcutaneous layer and is not as dependent on the chemical nature of the drug. Once the drug has been absorbed in the stomach and gut to make its way to the bloodstream. The blood then distributes these chemicals into the fluids in and around cells by binding to plasma proteins.

During distribution the drug is distributed by the blood to the necessary and targeted tissues and cells throughout the body in an effort to metabolise the drug. The body modifies the drug during metabolisation in order to make it easier to excrete which is the final step in pharmacokinetics. The drug goes through a biotransformation in the liver after which it can be eliminated or excreted easily through bile, urine and faeces. 

The Stages of Pharmacokinetics (ADME):

  1. Absorption
  2. Distribution
  3. Metabolisation
  4. Eliminated/Excreted


Why You Should Consider Genetic Testing in South Africa

Your genetic makeup has a direct effect on the way a drug will affect your body as well as the rate the drug take to deliver its effect. Your genetics directly influences how effectively your body will metabolise the drug. GENE-Rx™ can help determines whether you are:

  • A poor metaboliser
  • Intermediate metaboliser
  • Normal metaboliser, or
  • Rapid or Ultra-Rapid metaboliser

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These factors will influence the drug and dosage that will be initially prescribed, eliminating the trial and error approach. The below chart from GENEWAY™ shows how your genes are catagorised by what kind of metaboliser they are for different drugs in a genetic test.