Drugs that are commonly associated with tolerance are the opiods and alcohols.
These drugs induce the hepatic enzyme - cytochrome P450 leading to accelerated metabolism of the drugs. What happens when you are tolerant to a drug is that, you will need higher dose of that same drug to produce same effect subsequently.
It is also possible to develop resistance to a drug. Resistance to a drug usually happens when you do not take a complete dosage of drug, thus allowing the microorganisms to adapt and withstand the previous destructive effect by the drug. This usually occurs mostly with antibiotics.
The role of pharmacogenomics in drug resistant
Pharmacogenomics is simply the study of how our gene or genetic make up affects how different individuals respond to drugs. The way you react or respond to a drug can at times vary from another person. Reason being that, your genome (all your genetic make up) varies from another person. The gene determines the type of protein you express.
All receptor are made up of protein which are product of gene. In a situation where there is an alterations or mutation in the gene that codes for receptor protein, this automatically leads to deformation in the protein molecular structure or production of abnormal receptors, thus leading to abnormal or ineffective functions of the receptor. This results to inability of the receptor to bind to drugs that would on a normal bind without resistance.
Genetic mutation or diseases can cause drugs receptor to become resistant to drugs and the best way to check this, is through the study of pharmacogenomics. Always bear in mind that, the way you respond to a drug always and most times differ from others. Even identical twins can react differently to drugs not minding that they are identical.
Of a truth, identical twins come from the same fertilized egg. For the fact that they share similar genetic profile does not make them identical in genetic make up. Identical twins are apparently not genetically identical.
Back to our discussion on receptors!
Receptors exhibit a unique phenomenon of becoming unresponsive or insensitive to drug. This phenomenon is known as tachyphylaxis. Let's briefly talk about it.
Desensitization and Tachyphylaxis
Have you ever noticed that, at some point, when you continually take a medication, it suddenly doesn't produce those severe side effects on you when compared to the initial first time you took the drug.
If you continually take the drug, you would observe that there is a continuous reduction in the effects and at some point, you won't feel the effects any longer.
Your inability to feel the effects is a sort of protective mechanism by the drug receptors to avoid its damage. This is known as tachyphylaxis.
By definition, tachyphylaxis also known as desensitization or refractoriness is the decreased, insensitive or unresponsive state of a drug receptor due to continuous stimuli it receives from drugs or due to the drug continuous administration.
Receptors employ this mechanism to ensure that there is no damage to its components. In a nutshell, It is a decreased biological response to a drug when given continuously.
A drug administrated continues to exert it action until at a point where it begins to decline in action.
A close look at the dose-response curve below says it all. You would observe there was a gradual increase in the pharmacological effect of the drug starting from point a until it reaches it's maximal pointb after which it begins to decline in potency.
Tachyphylaxis is one of the problem encountered when a drug is expected to be continually administered or when they liable and susceptible to easy degradation by liver enzymes.
So since this is a major challenge in drug administration , what then is the way forward? Well the solution is not far fetched, thanks to advancement in drug discovery and the technology associated with it.
Rather than excessive administration of a particular drug, they could actually be made to stay longer and exert their therapeutic effects.
This leads us to the discovery of pharmacokinetic enhancers. We will look at the concept of pharmacokinetics enhancers.
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