Medication interactions

Pharmacodynamic Interactions. Sometimes medications interact pharmacody-namically. If two medications produce similar side effects, then those effects can be additive. This can be advantageous. For examples, coadministering two antidepressants that relieve depression in different ways can be more effective than either medication alone. However, added effects can be problematic. If two medications that each produce drowsiness are coadministered, then the combination may produce intolerable daytime sedation. 

Moclobemide, a reversible MAOI, is available in Europe and Canada. Because it is reversible, moclobemide has little risk of diet or medication interactions. 

What Is a Side Effect This chapter picks up where Chapters 1 and 2 left off. As we discussed in the earlier chapters, all medications, psychiatric and otherwise, have multiple effects. One takes a medication to achieve a therapeutic effect. Occasionally, a single medication may have more than one therapeutic effect. All other effects are side effects. Different medications may have differing therapeutic and side effects depending on the intended use. For example, trazodone and quetiapine are often prescribed to aid in sleep, and in this instance sedation is the desired effect, yet when used as an antidepressant and antipsychotic, respectively, the sedation is often an unwanted effect. Psychotropic medications typically have multiple effects. First, they usually interact with more than one nerve cell protein, be it a transporter or a receptor. Quite often, one of the medication s receptor or transporter interactions produces the therapeutic effect. The other interactions tend to not be involved in the therapeutic effect and only serve to produce side effects. Sometimes a neurotransmitter will have multiple different receptor types, but the medication interacts with... 

Don t, however, jump to the conclusion that it s always a bad thing when a medication interacts with more than one type of receptor. Sometimes, the combination of interacting with two different receptor types can produce even greater therapeutic benefit or can circumvent certain side effects. 

As we move forward with our discussion, we ll devote a section of this chapter to each of the key neurotransmitter systems that psychotropic medications interact with. We will discuss the following systems norepinephrine, dopamine, serotonin, GABA, acetylcholine, and histamine. Within each of the sections is a description of the effects that can be anticipated when a medication enhances the activity of that transmitter (reuptake inhibitors or agonists), and the effects to expect when a medication interferes (receptor antagonists) with the activity of that same transmitter. We will then describe strategies that can be implemented to help minimize and/or manage these side effects. 

This chapter will review the characteristics and regulatory properties of a2 receptors, neuropharmacology of the a2-adrenergic agonists, hypothesized mechanisms by which these medications alter central nervous system (CNS) activity, as well as a variety of issues related to their clinical use, including safety and adverse effects, dosing, and medication interactions. 

Munera PA, Perel JM, Asato M. Medication interaction causing seizures in a patient with bipolar disorder and cystic fibrosis. J Child Adolesc Psychopharmacol 2002 12(3) 275-6. 

Bohets H, Lavrijsen K, Hendrickx J et al. Identification of the cytochrome P450 eirzymes involved in the metabolism of cisapride In vitro stLidies of potential co-medication interactions. Br J Pharmacol 2000 129 1655-67. 

Medication interactions have been found to be poorly monitored. Medications are often necessary, and interactions can be handled in a manner in which the patient does not experience adverse effects and yet receives the benefit of appropriate medications. 

The Commission for Marketing Authorisations is consulted for all MA applications for medicines (Authorisation de Mise sur le Marche des Medicaments [AMM]) in Article R 5140 of the Code of Public Health as well as all requests for authorisation for temporary use (ATU). It encompasses a number of specialist working groups including pharmaceutics, toxico-pharmaco-clinical, antibiotic, medical interactions, AIDS, biotechnology, self-medication, and medical gases. 

Behavioral pharmacology The study of how medication interacts with human behavior... 

Medication Interaction between two medications can increase or decrease absorption when both... 

Medication Interaction A medication increases or decreases the pharmaceutical response of a previously administered medication. 

Food-medication interaction Determine if food interacts with medication. A food-drug interaction may result in an adverse effect. At times, medication is taken with food to reduce an upsetting side effect of the medication. On the other hand, food can slow absorption for some medications. 

MAOIs Most Common Side Effects and Possible Medication Interactions... 

A major concern is the effect herbal therapy has on the patient who is also taking prescribed medications. Medication interaction is always a risk. A prescriber should always ask what medication the patient is taking and review the patient s chart before prescribing another medication. 

The client should not take any over-the-counter medications without first consulting with the HCP or pharmacist because many medications interact with Cerebyx. 

MEDICATION MEMORY JOGGER Usually if there is a question regarding alcohol consumption and medication interaction, the recommendation is to avoid alcohol altogether, not limit the intake. 

This medication interacts with aspirin, warfarin, erythromycin, and theophylline therefore, this statement warrants further intervention by the nurse. 

Grapefruit juice does not specifically affect SSRIs, but the nurse should be aware that many medications interact negatively with grapefruit juice and its consumption should not be encouraged. 

Selected food hypersensitivity and medication interaction mainly due to one or more excipients may also preclude use of certain medications as listed in Table 4.3. 

Weathermen R, Crabb DW. Alcohol and medication interactions. Alcohol Res HeaMi (1999)... 

Drug mteractions between opioids and antiretroviral medications interaction between methadone, LAAM, andnelfinavir./lm (2004) 13,163 -80. 

Teleconsultation Medical interaction between a health care provider and a patient through telemedicine. 

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