Taking a drug while having certain medical conditions can also cause a drug interaction. For example, taking a nasal decongestant if you have high blood pressure may cause an unwanted reaction. A drug interaction can affect how a drug works or cause unwanted side effects. But drug interactions can complicate HIV treatment.
Health care providers carefully consider potential drug interactions before recommending an HIV treatment regimen. Before taking HIV medicines, tell your health care provider about all prescription and nonprescription medicines, vitamins, nutritional supplements, and herbal products you are taking or plan to take.
There are three types of drug interactions: Drug-drug interaction : A reaction between two or more drugs. Drug-food interaction : A reaction between a drug and a food or beverage. Drug-condition interaction: A reaction that occurs when taking a drug while having a certain medical condition. Drug Interaction. However, there are some medications whose metabolism is primarily governed by phase II metabolism, such as lamotrigine Lamictal , morphine and lorazepam Ativan. Phase II metabolism is catalyzed by specific enzymes, which are associated with specific substrates, inhibitors and inducers in a manner similar to phase I metabolism.
The P-glycoprotein transporter, however, does not affect drug metabolism, but rather drug bioavailability. P-glycoprotein is an adenosine triphosphate-dependent extruding transporter that lines the gut lumen and the blood-brain barrier.
It removes P-glycoprotein substrates from the cytosol of enterocytes and returns them back into the gut lumen or from the capillaries of the blood-brain barrier back into the bloodstream.
P-glycoprotein inhibitors antagonize this process and lead to retention of P-glycoprotein substrates. P-glycoprotein inducers increase the amount of active P-glycoprotein, thus leading to more extrusion of P-glycoprotein substrates.
A few cases may serve to clarify how an appreciation of these systems can help us understand and hopefully avoid drug-drug interactions. Case 1. Over the following 10 days, she experienced increasing dizziness, dry mouth and inability to void. She eventually required transportation to the emergency department ED , where a bladder catheterization yielded two liters of dark urine. Her INR was found to be This is an example of an inhibitor added to two substrates, whose effects synergized to produce the complications described above.
First, warfarin's metabolism mostly occurs at 2C9 for the more active S-isomer of warfarin Heimark et al. Fluoxetine in concert with its active metabolite, norfluoxetine is a strong 2D6 inhibitor and a moderate inhibitor of 2C9, 2C19 and 3A4 Greenblatt et al. Thus, the addition of the fluoxetine significantly impaired the ability of 2C9 to efficiently metabolize the warfarin, which led to an increase in the warfarin blood level.
This drastically increased the anticoagulant effect of warfarin. Second, amitriptyline is a tertiary amine tricyclic antidepressant whose metabolism depends mostly on the intact functioning of 2D6, 3A4 and 2C19 Venkatakrishnan et al.
As above, the fluoxetine and norfluoxetine significantly impaired the ability of 2D6, 3A4 and 2C19 to contribute to the metabolism of amitriptyline, which led to an increase in the blood level of amitriptyline and nortriptyline. The resultant increase in anticholinergic tone led to the inability to void and subsequent bladder wall distension. These combined effects of a hypocoagulable state and anticholinergic-induced urinary retention led to spontaneous bleeding within the patient's distended bladder.
Case 2. She unfortunately required hospitalization for a breakthrough manic episode. She had a history of poorly tolerating lithium Eskalith, Lithobid and antipsychotic medications even atypical agents. Her psychiatrist decided to try oxcarbazepine Trileptal , titrated to mg bid, and lorazepam Ativan for control of agitation. The patient's manic symptoms gradually improved, and she was discharged after a day hospital stay.
However, three weeks later, the patient experienced an emergence of depressive symptoms. This is an example of an inducer added to a substrate. Brager R, Sloand E The spectrum of polypharmacy. Nurse Pract 30 6 — Pharmacotherapy 25 11 — Frazier SC Health outcomes and polypharmacy in elderly individuals: an integrated literature review. J Gerontol Nurs 31 9 :4— J Am Acad Nurse Pract 17 4 — Clin Ther 35 4 — Wongpoowarak W, Wongpoowarak P Unified algorithm for real-time detection of drug interaction and drug allergy.
Comput Methods Programs Biomed 68 1 — Barrons R Evaluation of personal digital assistant software for drug interactions. Am J Health Syst Pharm 61 4 — London, UK: Pharmaceutical Press; Ann Pharmacother 47 10 : Download references.
You can also search for this author in PubMed Google Scholar. Correspondence to Mitja Lainscak. Reprints and Permissions. Roblek, T. Drug-drug interaction software in clinical practice: a systematic review.
Eur J Clin Pharmacol 71, — Download citation. Received : 28 July Accepted : 18 November Published : 23 December Issue Date : February Anyone you share the following link with will be able to read this content:. Sorry, a shareable link is not currently available for this article.
Provided by the Springer Nature SharedIt content-sharing initiative. Skip to main content. Search SpringerLink Search. In general, however, the screen menus, appearance of the programs, and the "extras" included in each program differ more than the programs' drug interactions output.
The software programs tested are all easy to use.
0コメント