OBJECT DRUGS

Central Alpha-adrenergic Agonists:

• Clonidine (Catapres, etc.)
• Guanabenz (Wytensin)
• Guanfacine (Tenex, etc.)

PRECIPITANT DRUGS

Antidepressants:

• Amitriptyline (Elavil)
• Amoxapine (Asendin)
• Clomipramine (Anafranil)
• Desipramine (Norpramin)
• Doxepin (Sinequan, etc.)
• Duloxetine (Cymbalta)
• Imipramine (Tofranil, etc.)
• Mirtazapine (Remeron, etc.)
• Nortriptyline (Aventyl, etc.)
• Protriptyline (Vivactil)
• Trimipramine (Surmontil)

Comment:

ricyclic antidepressants (TCAs) can markedly reduce the antihypertensive effects of clonidine, guanfacine, and probably guanabenz. The effect is usually gradual but rapid increases in blood pressure have occurred. Also, stopping clonidine-like drugs abruptly in the presence of TCAs may result in an acute hypertensive reaction.

Class 2: Use Only if Benefit Felt to Outweigh Risk

• Use Alternative:
• Antidepressant: Limited evidence suggests that trazodone (Desyrel) may also inhibit the effect of clonidine. Theoretically, serotonin-norepinephrine reuptake inhibitors (SNRI) such as desvenlafaxine (Pristiq), duloxetine (Cymbalta), milnacipran (Savella), and venlafaxine (Effexor) would also be expected to inhibit the antihypertensive effects of clonidine-like drugs, so SNRIs may not be suitable alternatives. Little is known regarding the effect of other antidepressants, but use alternative antidepressants only with careful blood pressure monitoring.
• Antihypertensives: Beta-adrenergic blockers, diuretics, ACEIs, ARBs, and calcium channel blockers appear to be minimally affected by TCAs. Be alert to the potential for diltiazem (Cardizem) and verapamil (Calan) to inhibit the metabolism of some TCAs. The efficacy of guanethidine (Ismelin) and guanadrel (Hylorel) is also inhibited by TCAs.
• Circumvent/Minimize:In patients receiving central alpha agonists and TCAs, clonidine-like drugs should be tapered instead of stopped abruptly to reduce the likelihood of a hypertensive reaction.
• Monitor: In patients on central alpha-receptor agonists, monitor blood pressure carefully if TCAs are initiated, discontinued, or changed in dosage.