W-3 Enzymes

CYP1A2 Enzyme by Edina Boros

The following discussion will examine the enzyme CYP1A2, one of the five most significant enzymes in the cytochrome P450 (CYP) system (Stahl, 2013). This discussion post will detail the significance of this enzyme, the interaction with medications, and the impact on clinical practice.

The Cytochrome P450 enzymes have an essential role in metabolizing drugs. Genetic variability can be a factor that influences the enzyme’s function. Each enzyme has a specific gene responsible for the function of that enzyme. The inherited alleles determine how a person responds to certain drugs. Specific medications can affect the operation of CYP 1A2 differently, leading to adverse reactions and therapeutic failure (Lynch&Neff, 2007). The enzyme CYP1A2 is expressed mainly in the liver but can be found in the small intestine, the lungs, the kidneys, and the placenta (Lynch &Neff, 2007).

One or more CYP 450 enzymes can metabolize medications. CYP1A2 has a role in processing clozapine, olanzapine, fluvoxamine, haloperidol, theophylline, melatonin, bilirubin, estrogens, procarcinogens, and caffeine. Caffeine is almost entirely metabolized by CYP1A2. Caffeine consumption and cigarette smoking induce CYP1A2 activity, which should be considered when prescribing medications. Known methods of estimating enzyme activity are testing caffeine clearance or determining the concentration ratio of paraxanthine, the primary caffeine metabolite, to caffeine in a saliva sample (Urry et al., 2016).

Some medications such as Amiodarone, cimetidine, ciprofloxacin, and fluvoxamine are potent inhibitors. Inhibition of the enzyme means that drug levels in the blood can reach higher than expected levels, which can be a potential safety issue (Alsanosi & Padmanabhan, 2014).

Known inducers of CYP1A2 are Carbamazepine, phenobarbital, rifampin, tobacco. These substances can lower the desired serum level of certain medications. Although it happens with some delay, it has to be considered when added to medicines metabolized by the same enzyme. There are available substitute medications or increasing or decreasing the dosages of the target medication to avoid therapeutic failure or adverse effects. Substrates affecting the CYP1A2 enzymes are caffeine, clozapine, and theophylline (Lynch Neff, 2007).

References

Alsanosi, S. M. M., Padmanabhan, S. (2014). Enzyme inhibition. Enzyme Inhibition - an overview | ScienceDirect Topics. Retrieved September 17, 2021, from https://www.sciencedirect.com/topics/neuroscience/enzyme-inhibition.

Ghodke-Puranik, Y. A., & Lamba, J. K. (2017). CYP1A2 - an overview | ScienceDirect Topics. Retrieved September 17, 2021, from https://www.sciencedirect.com/topics/medicine-and-dentistry/cyp1a2.

Lynch, T.,&Neff, A. P. (2007, August 1). The effect of Cytochrome P450 metabolism on Drug Response, interactions, and adverse effects. American Family Physician. Retrieved September 17, 2021, from https://www.aafp.org/afp/2007/0801/p391.html.

Stahl, S. (2013). Essentials of Psychopharmacology, (4th edition). United Kingdom: Cambridge University Press.

Urry, E., Jetter, A., & Landolt, H. P. (2016). Assessment of CYP1A2 enzyme activity in relation to type-2 diabetes and habitual caffeine intake. Nutrition & metabolism, 13(1), 1-9.