Medications & Therapy

Drugs do not have the same effect in all patients. This is due to many factors including an individual´s genetic make-up.

In order to achieve optimal function, a drug needs to reach a certain concentration in the body and stay at this concentration for a given period of time. Correct dosing of a drug needs to take into account the speed at which it is degraded and eliminated by the body. Furthermore, it needs to be considered that some drugs (“prodrugs”) are only effective after activation by enzymes of the body. Enzymes metabolizing (inactivating and activating) drugs are encoded by specific genes. Variants of these genes influence the activity of the enzymes. This genetic variation is one of several reasons why efficacy and tolerance of drugs vary greatly between individuals. Genetic tests for variants affecting metabolism of drugs thus facilitate individualized medical treatment. This keeps un-wanted side-effects to a minimum. Individualized medication is greatly desirable given that only 25-60% of drugs act optimally at doses recommended by the manufacturer.

Genes involved in metabolism of given drugs are listed in pharma.sensor. PGS.box “Pharma” tests relevant genes.

Examples of usefulness of PGS.box „Pharma“

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Pain medication (example codeine)

Codeine is used in many medications including cough syrups and drops. The rate of activation of this prodrug varies greatly in individuals. This explains why the same dose of codeine can be toxic in one and almost non-functional in another person. Determination of genetic variants of the gene CYP2D6 that are associated with slow or rapid activation of codeine, can be useful to select alternative and more optimal medications.

  1. Many cough medications contain codeine. The enzyme CYP2D6 mediates conversion of codeine into morphine. Some variants of the CYP2D6 gene result in extremely high activity of the enzyme.
  2. If people are aware of this change, they can take the advice of doctors.
  3. Knowledge of such variants helps people to consult a physician for codeine-free cough medications or medications with reduced doses of codeine.
  4. A reduced dosage helps to avoid adverse drug reactions.

 

Cancer medications (example tamoxifen)

Tamoxifen is a prodrug and used for treatment of breast cancer. There are several variants of the gene CYP2D6 that are associated with insufficient or absent activity of the enzyme. As a result tamoxifen does not function in patients with these variants. PGS identifies persons who do not respond to treatment with tamoxifen and require alternative medications.