Is extended clonazepam cotherapy of fluoxetine effective for outpatients with major depression?

Clonazepam cotherapy of fluoxetine was previously demonstrated to accelerate efficacy over the first 3 weeks of treatment. A new 18-week double-blind study attempted to replicate these findings to determine whether superiority would extend to 3 months and assess risks of extension.

Fifty outpatient volunteers aged 18-65 from Seattle and Portland with moderate-marked depression received fluoxetine (20 mg) doubled at 6 weeks if needed; half took clonazepam (0.5 mg) and half took an identical placebo, 1 or 2 tablets adjusted during the first 2 weeks, until a 3-week taper at 3 months.

No serious adverse events and no special problems with sedation or discontinuation were noted. Cotherapy was superior to fluoxetine monotherapy at Day 7 for HAM-D (t=2.03, df=48, P<0.05) and CGI-I (32 vs. 4% responders, P<0.03, Fisher Exact Test) but not otherwise. Cotherapy was effective in reducing insomnia but not anxiety or core symptoms (low mood, suicidality, reduced interest). The only significant benefit of extending treatment was a more rapid response to increased fluoxetine at 6 weeks manifested in a mean HAM-D of 9.0 and CGI-I responder rate of 76% after 8 weeks compared to 16 weeks for monotherapy.

Small sample size (N=50) limited power and rendered conclusions tentative.

Extended clonazepam cotherapy of fluoxetine appeared safe and effective for depressed outpatients: it was superior to fluoxetine alone early in treatment and again following fluoxetine dose increase. Cotherapy might be considered at the start of fluoxetine treatment, especially for those with insomnia, and when a dose increase of fluoxetine is anticipated.