MAOIs drug interactions with

In addition to this serious diet-drug interaction, irreversible MAOIs also potentiate the effects of sympathomimetic drugs like ephedrine found in over-the-counter cold remedies and recreational stimulants like amphetamine. The MAOIs also interact with drugs that increase synaptic concentrations of 5-HT, such as the tricyclic antidepressant clomipramine and the herbal SSRI antidepressant St John s wort (Hypericum spp.). The resulting serotonin syndrome is characterised by hyperthermia and muscle rigidity. While devoid of these side effects the reversible MAO-A inhibitor moclobemide has yet to establish itself as a first-line alternative to the SSRIs. 

Antidepressants are commonly prescribed with other psychotropic and nonpsychotropic agents. There is potential for drug interactions with all antidepressants, but the most serious of these involve the MAOIs and to a lesser extent the TCAs. 

Q8 A pregnancy test is necessary because hypertension is a feature of preeclampsia, a serious condition which can occur in pregnancy and which threatens the life of both mother and foetus. Also, many antihypertensive drugs are contraindicated in pregnancy. It is necessary to know whether the patient is taking prescribed medicines or is self-medicating, as some drugs, such as monoamine oxidase inhibitors (MAOIs), can interact with dietary components to cause a very rapid rise in BP. 

Patient shouid be advised not to take any prescription or over-the-counter drugs without consuiting their doctor because of possibie drug interactions with the MAOi... 

Ephedra has been closely linked to methamphetamine production. There are movements In many localities to outlaw the herb. There are many drug interactions with Ma huang. )9-BI(K kcrs may enhance the sympathetic effect and cause hypertentiion. MAOIs may interact with ephedra to cause hypertensive cri.si.s. Phcnothiaz.ines might block the or effects of ephedra, causing hypotension and tachycardia. Simultaneous use of theophylline may cau.se GI and CNS effects. In pregnancy, ephedra is absolutely contraindicated (uterine stimulation). Persons with heart disease, hypertension, and diabetes should not take ephedra. 

Buspirone is a well-tolerated drug, the most commonly reported side effects being transient dizziness, light-headedness, headache, and gastrointestinal disturbances. Other limitations of buspirone are its delayed onset of action (fewday s to a few weeks) and a significant drug interaction with MAOIs. 

One serious adverse reaction associated with the use of the MAOIs is hypertensive crisis (extremely high blood pressure), which may occur when foods containing tyramine (an amino acid present in some foods) are eaten (see Home Care Checklist Avoiding Drug Food Interactions With MAOIs). 

AVOIDING DRUG-FOOD INTERACTIONS WITH MAOIs... 

If the patient is prescribed an MAOI, it is critical that the nurse give the patient a list of foods containing tyramine. When teaching the patient, the nurse emphas zesthe importance of not eating any of the foods on the list. (See Home Care Checklist Avoiding Drug-Food Interactions With MAOIs)... 

Because of their lack of selectivity and their irreversible inhibition of MAO, the first MAOIs to be developed presented a high risk of adverse interactions with dietary tyramine (see Chapter 20). However, more recently, drugs which are selective for and, more importantly, reversible inhibitors of MAO-A (RIMAs) have been developed (e.g. moclobemide). These drugs are proving to be highly effective antidepressants which avoid the need for a tyramine-free diet. 

The main problems with early, irreversible MAOIs were adverse interactions with other drugs (notably sympathomimetics, such as ephedrine, phenylpropanolamine and tricyclic antidepressants) and the infamous "cheese reaction". The cheese reaction is a consequence of accumulation of the dietary and trace amine, tyramine, in noradrenergic neurons when MAO is inhibited. Tyramine, which is found in cheese and certain other foods (particularly fermented food products and dried meats), is normally metabolised by MAO in the gut wall and liver and so little ever reaches the systemic circulation. MAOIs, by inactivating this enzymic shield, enable tyramine to reach the bloodstream and eventually to be taken up by the monoamine transporters on serotonergic and noradrenergic neurons. Fike amphetamine, tyramine reduces the pH gradient across the vesicle membrane which, in turn, causes the vesicular transporter to fail. Transmitter that leaks out of the vesicles into the neuronal cytosol cannot be metabolised because... 

Each antidepressant has a response rate of approximately 60% to 80%, and no antidepressant medication or class has been reliably shown to be more efficacious than another 22 MAOIs may be the most effective therapy for atypical depression, but MAOI use continues to wane because of problematic adverse effects, dietary restrictions, and possibility of fatal drug interactions.22,28 There is some evidence that dual-action antidepressants, such as TCAs and SNRIs, may be more effective for inpatients with severe depression than are the single-action drugs such as SSRIs,22,28 but the more general assertion that multiple mechanisms of action confer efficacy advantages is quite controversial.33... 

Changing a patient from one MAOI to another, or to a TCA, requires a "wash-out" period of at least 2 weeks to avoid the possibility of a drug interaction. There is evidence to suggest that a combination of an MAOI with clomipramine is more likely to produce serious adverse effects than occurs with other TCAs. Regarding the newer non-tricyclic antidepressants, it is recommended that a "wash-out" period of at least 5 weeks be given before a patient on fluoxetine is given an MAOI this is due to the very long half-life of the main fluoxetine metabolite norfluoxetine. 

Drugs that may interact with buprenorphine hydrochloride include barbiturate anesthetics, benzodiazepines, CNS depressants, CYP3A4 inducers and inhibitors, and MAOIs. 

Drugs that may interact with atomoxetine include albuterol, CYP2D6 inhibitors, MAOIs, and pressor agents. 

Some chemical exposures may be hepatic enzyme inducers/inhibitors, altering the effects of drugs like warfarin. Some foods such as mono-amines, will cause reactions in patients given MAOIs grapefruit juice may interact with terfenadine and some other drugs. New diseases may cause problems heart failure causing reduced liver blood flow can reduce the metabolism of drugs like warfarin. 

The most common reason for the underutilization of MAOIs is the potential for serious consequences of MAOI drug-food and drug-drug interactions. Combined MAOI treatment with (1) foods or medications involved in monoamine synthesis (2) monoamines themselves or (3) other sympathomimetics routinely found in over-the-counter medications can result in hy-peradrenergic crises or serotonin toxicity (Blackwell, 1991). 

The second major drug interaction involves combining MAOIs with serotonergic drugs, resulting in excessive... 

Not long after their introduction, it was discovered that MAOIs could have serious and sometimes fatal interactions with other medications and foods that have high levels of tyramine. Tyramine is found in foods like cheese, wine, beer, liver, and even chocolate, and can increase blood pressure. MAOIs interact with certain medications and foods, raising blood pressure so much that fatal results can occur. To be used safely, these drugs must be taken with a restricted diet. 

Inhibition of MAO can cause severe interactions with other drugs, as detailed in the Hypertensive Crisis and Serotonin Syndrome subsections earlier in this section. A list of drugs that interact with the nonselective MAOIs is provided in Table 2-5. 

Although most physicians avoid the combination of an MAOl with most other antidepressants, a number of reports indicate that MAOIs combined with a TCA can be effective and safe in treatment-resistant patients. This combination should be used only by a physician skilled in their use and familiar with their potential adverse effects and drug interactions. Generally, tertiary amine TCAs have been used in combination with MAOIs. Once the dose of the TCA is established, the MAOl should be slowly added. Never attempt the reverse order without a 2-week delay. It may also be prudent to lower the TCA dose slightly before starting the MAOl. An example might be the addition of phenelzine to amitriptyline, starting with an initial dose of 15 mg and subsequent dose increments weekly as needed. The total dose of an MAOl, used in combination with TCA, is usually lower than when used alone (e.g., 30 to 60 mg per day). When the combination is discontinued, the MAOl should be stopped first. 

Newer MAOI drugs are selective for the MAO-A subtype of the enzyme, and are less likely to interact with foods or other drugs. Monoamine oxidase (MAO) inactivates monoamine substances, many of which are, or are related to, neurotransmitters. The central nervous system mainly contains MAO-A, whose substrates are adrenaline (epinephrine), noradrenaline (norepinephrine), metanephrine, and 5-hydroxyti7ptamine (5-HT), whereas extra-neuronal tissues, such as the liver, lung, and kidney, contain mainly MAO-B which metabolises p-phenylethylamine, phenylethanolamine, o-tyramine, and benzylamine. 

The most common interactions with SSRIs are pharmacokinetic interactions. For example, paroxetine and fluoxetine are potent CYP2D6 inhibitors (Table 30-4). Thus, administration with 2D6 substrates such as TCAs can lead to dramatic and sometimes unpredictable elevations in the tricyclic drug concentration. The result may be toxicity from the TCA. Similarly, fluvoxamine, a CYP3A4 inhibitor, may elevate the levels of concurrently administered substrates for this enzyme such as diltiazem and induce bradycardia or hypotension. Other SSRIs, such as citalopram and escitalopram, are relatively free of pharmacokinetic interactions. The most serious interaction with the SSRIs are pharmacodynamic interactions with MAOIs that produce a serotonin syndrome (see below). 

Trazodone Hydrochloride Trazodone overdose causes severe toxic effects. These effects are severe if taken along with benzodiazepines or alcohol. Trazodone interacts with MAOIs, cardiovascular drugs, CNS depressants, and antiepileptics. 

Viloxazine Hydrochloride Viloxazine hydrochloride interacts with MAOIs, cardiovascular drugs, CNS drugs, and antiepileptics. 

Sulfonylureas In acute poisoning with sulfonylureas, the stomach should be washed and treated with activated charcoal, and hypoglycemia must be treated. Sulfonylureas interact with oral contraceptives, thiazide diuretics, corticosteroids, adrenaline, chlorpromazine, ACE inhibitors, some NSAIDs, antihistamines, anticoagulants, MAOIs, antidepressants, and many other drugs. Care must be exercised when treating with sulfonylureas. 

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