Monoamine oxidase inhibitors monitoring

Plasma levels of doxepin similar to those achieved during oral therapy may be obtained with topical application the usual drug interactions associated with tricyclic antidepressants may occur. Therefore, monoamine oxidase inhibitors must be discontinued at least 2 weeks prior to the initiation of doxepin cream. Topical application of the cream should be performed four times daily for up to 8 days of therapy. The safety and efficacy of chronic dosing has not been established. Adverse local effects include marked burning and stinging of the treatment site which may necessitate discontinuation of the cream in some patients. Allergic contact dermatitis appears to be frequent, and patients should be monitored for symptoms of hypersensitivity. 

Patients taking monoamine oxidase inhibitors, anticholinergic drugs (such as tricyclic antidepressants), propranolol, reserpine, guanethidine, and methyldopa should be monitored closely if phenylephrine is used (SEDA-16, 542) (16). 

Antidepressant drugs A major class of psychotropic drugs with diverse chemical configurations including the monoamine oxidase inhibitors (MAOIs), the heterocyclic drugs (composed of mono-, di-, tri-, and hetero-cyclics), the serotonin reuptake inhibitors (fluoxetine, paroxetine, sertraline, trazodone, and venlafaxine), and bupropion are more recent innovations. Antidepressants usually must be taken for several weeks to have the desired effect and they often have a low therapeutic index, so they must be closely monitored. 

Use of monoamine oxidase inhibitors (MAOI) antidepressant blood levels to monitor patients with depression is of no clinical value. 

Interactions The vitamin pyridoxine (B6) increases the peripheral breakdown of levodopa and diminishes its effectiveness (Figure 8.6). Concomitant administration of levodopa and monoamine oxidase (MAO) inhibitors, such as phenelzine (see p. 124), can produce a hypertensive crisis caused by enhanced catecholamine production therefore, caution is required when they are used simultaneously. In many psychotic patients, levodopa exacerbates symptoms, possibly through the buildup of central amines. In patients with glaucoma, the drug can cause an increase in intraocular pressure. Cardiac patients should be carefully monitored because of the possible development of cardiac arrhythmias. Antipsychotic drugs are contraindicated in parkinsonian patients, since these block dopamine receptors and produce a parkinsonian syndrome themselves. 

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