Posted by SalArmy4me on August 26, 2001, at 21:59:17
In reply to EFFEXOR increase from 150mg to 300mg..HELP!!, posted by Firebabe on August 26, 2001, at 18:22:52
Journal of Clinical Psychopharmacology
Benztropine for Venlafaxine-Induced Night Sweats
Pierre, Joseph M. MD; Guze, Barry H. MDMs. B., a 28-year-old woman with borderline personality disorder, was managed as an outpatient with venlafaxine 150 mg taken twice daily for depression. The dose was decreased after the development of night sweats that would soak her clothes; were not associated with other symptoms such as panic, anxiety, hot flashes, or fever; and resolved when venlafaxine was decreased below 150 mg/day. She used diphenhydramine for anxiety and venlafaxine 37.5 to 75 mg thrice daily for several months until being hospitalized for worsening depression and self-mutilation. Physical examination and laboratory studies, including levels for her white blood cell count, thyroid-stimulating hormone, and free thyroxin, were normal. The venlafaxine dose was increased to 150 mg twice daily, clonazepam 0.5 mg twice daily as needed was given for anxiety, and zolpidem 10 mg at bedtime as needed was given for insomnia and replaced diphenhydramine, and risperidone 2 mg twice daily was added for delusional intrusive thoughts. She improved and was discharged after 1 week. As an outpatient, Ms. B. self-discontinued risperidone and again experienced night sweats, which remitted after decreasing the venlafaxine dose to 150 mg/day. She was readmitted to the hospital, at which time risperidone 2 mg twice daily was restarted. A short trial of nefazodone was attempted in place of venlafaxine, but it was not tolerated because of hypotension and syncope. She was discharged on venlafaxine 75 mg twice daily and risperidone 2 mg at bedtime. After 5 weeks, Ms. B. was hospitalized for a third time. She had again discontinued risperidone, but was tolerating venlafaxine 75 mg twice daily without night sweats. Olanzapine 10 mg at bedtime was started, and venlafaxine was again increased to 150 mg twice daily. Within 5 days of taking this dose of venlafaxine, night sweats recurred. The night sweats resolved with the addition of benztropine 0.5 mg at bedtime and recurred at home after discharge without it. Restarting benztropine helped. Because of dry mouth, benztropine was decreased to 0.5 mg every other night, yielding fair control of night sweats. Ms. B. tolerated venlafaxine 187.5 mg twice daily. Olanzapine was increased to 15 mg/day, and lorazepam 1 mg twice daily as needed for anxiety replaced clonazepam. She described occasional attenuated night sweats (her clothes were not drenched) only on the nights without benztropine. After 1 month, the night sweats became more frequent and were refractory to daily benztropine. She self-discontinued venlafaxine and was subsequently started on fluoxetine without further night sweats.
Discussion
Sweating is a known side effect of venlafaxine that may cause patients to discontinue pharmacotherapy.1 Ms. B. experienced night sweats (drenching sweats during sleep) with venlafaxine. Because it is not clear whether previous data on antidepressant-induced sweating include this variant, it seems that this side effect has not been previously reported.The pathophysiology of night sweats may differ from sweating in general and has a differential diagnosis that includes infection, neoplasm, and endocrinopathy, in addition to antidepressant side effects.2 Ms. B.'s night sweats were not attributable to medical illness given the absence of laboratory abnormalities or associated signs and symptoms. They did have a temporal and dose relationship to venlafaxine. The package insert for venlafaxine indicates an increased incidence of sweating with increasing dose (Effexor [venlafaxine] package insert. Philadelphia: Wyeth Laboratories, 1996). Ms. B.'s threshold dose for night sweats was 300 mg/day.
The mechanism of venlafaxine-induced sweating is unclear, but presumably involves increased norepinephrine, stimulating both the preganglionic sympathetic cholinergic fibers innervating the sweat glands and the subpopulation of [beta]-adrenergic receptors on the glands themselves.3 Ms. B.'s initial relief provided by benztropine is consistent with cholinergic blockade in the sweat glands, as suggested in a previously reported case of benztropine for venlafaxine-induced sweating.4 Ms. B.'s eventual development of tolerance to benz-tropine may represent inadequate cholinergic blockade to counter the noradrenergic effects of several weeks of venlafaxine dosed at 375 mg/day. One wonders whether an increase in her low dose of benztropine would have been helpful. Despite her sensitivity to the side effects of both benztropine (dry mouth) and venlafaxine (night sweats), which ultimately prompted a switch to another antidepressant altogether, benztropine seemed to have a temporizing benefit for Ms. B. that enabled her to tolerate several weeks of receiving a maximal dose of venlafaxine. The addition of benz-tropine for venlafaxine-induced night sweats may therefore facilitate administration of venlafaxine at potentially therapeutic doses for patients with this side effect. This potential benefit of benztropine should be weighed against the risk of its own side effects, ranging from the usual but consequential (such as Ms. B.'s dry mouth) to more toxic anticholinergic complications (such as tachycardia, ileus, hyperpyrexia, and delirium)."
Joseph M. Pierre, M
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