NU643: discussion week 3

For this assignment, choose one psychotropic drug that is metabolized by CYP450 enzymes and complete the following steps:

1. Write a summary introducing your chosen drug thoroughly in terms of its class, use, precautions, side effects, interactions, and overdose potential. Hypothesize the outcome of prescribing your chosen drug in the presence of its CYP450 inhibitor and inducer.
2. Answer the following questions:
   • What are examples of drugs that will inhibit and induce the psychotropic drug you chose to study? What will happen in terms of side effects and symptoms in the patient if the psychotropic drug is prescribed along with either its (1) inhibitor or (2) inducer?
   • For which CYP450 enzyme/s is it a substrate?
   • What are the pharmacokinetic considerations when prescribing this medication (i.e., absorption, distribution, elimination)? Dietary considerations? Dosing times?

One Psychotropic drug that is metabolized by CYP450 enzymes.

Theophylline is metabolized in the liver by the cytochrome p450 microsomal enzyme system, and a large number of factors may influence hepatic metabolism. Theophylline is predominantly metabolized but the CYP1A2 enzyme, while at higher plasma concentration (Beavo,2021).

The Theophylline class drugs is known as Xanthine. It works by relaxing the muscles around the airways so that they open, and you can breathe more easily. It also decreases the lungs’ response to irritants. Controlling symptoms of breathing problems can decrease time lost from work or school. Common symptoms and side effects of this medication is Nausea/vomiting, stomach/abdominal pain, headache, trouble sleeping, diarrhea, irritable, restlessness, shaking, or increased urination may occur (Weinberger,2022) As with other methylxanthines theophylline toxicity can lead to GI distress, insomnia, and tremor. This medication interacts with  phenytoin, propafenone, Rifampin. Theo decreases their absorption, Rifampin increases theophylline clearance by increasing cytochrome P450,1A2, and 3A3 activity. Drug that inhibits Theophylline metabolism such as Cimetidine, erythromycin, tacrine stopping, stopping a concurrently administered drug enhances theophylline metabolism such as carbamazepine, rifampin. The drugs that have been associated with increased theophylline clearance are relatively few; all are known to be inducers of cytochrome P-450 enzymes. Such agents include phenobarbital, phenytoin, carbamazepine, and tobacco smoke (person,2020) Theophylline is primarily eliminated by hepatic metabolism involving isoenzymes of the cytochrome p450 system. The metabolism has been assumed to follow. This medication can be once every 24 hours in patient who are nonsmokers. Theo can bind to the A2B receptor and blocks adenosine mediated bronchoconstriction.

 Reference:

Beavo J.A cyclic nucleotide phosphodiesterases (2021). Functional implications multiple isoforms ,Physio. Rev.

Estenne M, Yernault J. De Troyer A.(2022) effects of parenteral aminophylline on lung mechanics in normal humans AM. REV. Respir. dIs.

Persson C.G.A (2022) development of safer xanthine drugs for the treatment of obstructive airways disease. J. Allergy clin. Immunol 2022 817-824.

Weinberger ,Hendel’s L.(2020) Theophylline is asthma, New Engl .Jumped 2020 334:1380-1388.

By now, you have chosen your enzyme topic for this discussion forum:

• Topic 1: CYP 1A2 enzyme
• Topic 2: CYP 2D6 enzyme
• Topic 3: CYP 3A4 enzyme

For this discussion, each student will create a four to five slide PowerPoint presentation including voice-over that will be used to educate your fellow classmates on your chosen topic. Be creative in presenting your topic and include at least two references (in APA format) beyond Stahl for your information.

Please answer the following questions in your presentation.

• What is your enzyme?
• Why is it important?
• What does it do in the human body?
• What are the substrates, inhibitors and inducers of your enzyme?
• What are the important medication restrictions regarding this enzyme?