Sildenafil adjunctive therapy to risperidone in the treatment of the negative symptoms of schizophrenia: a double-blind randomized placebo-controlled trial.
BACKGROUND
It has been suggested that phosphodiesterase 5 inhibitors such as sildenafil may be effective in the treatment of negative symptoms of schizophrenia.


OBJECTIVE
This study was designed to investigate the effect of sildenafil added to risperidone as augmentation therapy in patients with chronic schizophrenia and prominent negative symptoms in a double-blind and randomized clinical trial.


METHODS
Eligible participants in the study were 40 patients with chronic schizophrenia with ages ranging from 18 to 45 years. All patients were inpatients and were in the active phase of the illness and met DSM-IV-TR criteria for schizophrenia. Patients were allocated in a random fashion: 20 to risperidone (6 mg/day) plus sildenafil (75 mg/day) and 20 to risperidone (6 mg/day) plus placebo. The principal measure of outcome was Positive and Negative Syndrome Scale (PANSS).


RESULTS
Although both protocols significantly decreased the score of the positive, negative, and general psychopathological symptoms over the trial period, the combination of risperidone and sildenafil showed a significant superiority over risperidone alone in decreasing negative symptoms and PANSS total scores over the 8-week trial (between-subjects factor; F = 4.77, df = 1; P = 0.03; F = 5.91, df = 1, P = 0.02 respectively).


CONCLUSIONS
Therapy with 75 mg/day of sildenafil was well tolerated, and no clinically important side effects were observed. The present study indicates sildenafil as a potential adjunctive treatment strategy for treatment of negative symptoms of schizophrenia. This trial is registered with the Iranian Clinical Trials Registry (IRCT1138901151556N11).
Psychiatric Research Center, Roozbeh Psychiatric Hospital, Tehran University of Medical Sciences, South Kargar Street, Tehran 13337, Iran. s.akhond@neda.net
Shahin
S
Akhondzadeh
Raofeh
R
Ghayyoumi
Farzin
F
Rezaei
Bahman
B
Salehi
Amir-Hossein
AH
Modabbernia
Azad
A
Maroufi
Gholam-Reza
GR
Esfandiari
Mehrangiz
M
Naderi
Fariba
F
Ghebleh
Mina
M
Tabrizi
Shams-Ali
SA
Rezazadeh
D000293:Adolescent; D000328:Adult; D014150:Antipsychotic Agents / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D004311:Double-Blind Method; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D058986:Phosphodiesterase 5 Inhibitors / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use; D010879:Piperazines / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D011446:Prospective Studies; D011569:Psychiatric Status Rating Scales; D011687:Purines / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use; D018967:Risperidone / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D012559:Schizophrenia / Q000188:drug therapy* / Q000503:physiopathology; D012565:Schizophrenic Psychology; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D055815:Young Adult
D014150:Antipsychotic Agents; D058986:Phosphodiesterase 5 Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D000068677:Sildenafil Citrate; D018967:Risperidone