Decreased serotonin content and reduced agonist-induced aggregation in platelets of patients chronically medicated with SSRI drugs.

BACKGROUND: Chronic treatment with selective serotonin reuptake inhibitors (SSRIs) reduces the risk and severity of cardiovascular diseases. SSRIs block the serotonin transporter, thereby inhibiting serotonin (5-HT) uptake into presynaptic neurons as well as into platelets where 5-HT is stored in dense granules. When 5-HT is released in response to agonists it enhances platelet aggregation induced by injury-related signals. Chronic administration of SSRIs may thus reduce platelet aggregability secondary to depletion of platelets' serotonin stores. METHODS: The study included ten DSM-IV-TR major depression (MDD) and four obsessive compulsive disorder (OCD) patients and fourteen healthy untreated age- and sex-matched controls. The patients were chronically medicated (6-108 months) with various SSRIs. Platelet serotonin content was assessed in fresh samples of platelet rich plasma (PRP) using radioimmunoassay. ADP, collagen, arachidonic acid and epinephrine were used as inducers of platelet aggregation measured in PRP by turbometric method in a microplate reader. RESULTS: Lower platelet serotonin content (66%; p<0.05) and lower ADP, collagen or epinephrine-induced platelet aggregation (10-52%; p<0.05) were detected in PRP of SSRI-medicated patients, while no such effect was obtained with arachidonic acid. LIMITATIONS: The small sample size and the co-treatment with non-SSRI drugs such as benzodiazepines. CONCLUSION: Patients chronically medicated with SSRIs exhibit lower platelet 5-HT content and reduced platelet aggregation induced by ADP, collagen and epinephrine, but not by arachidonic acid. Our observations may explain the increased bleeding risk associated with chronic SSRI treatment as well as the reported beneficial effect of SSRIs in prevention of recurrent myocardial infarction.

A naturalistic long-term comparison study of selective serotonin reuptake inhibitors in the treatment of panic disorder.

OBJECTIVES: Selective serotonin reuptake inhibitors (SSRIs) are currently considered as the first drug of choice in the treatment of panic disorder (PD). The aim of this long-term, naturalistic comparison study was to compare 4 SSRIs with respect to tolerability and treatment outcome of PD. Outcome measures included relapse rates and adverse effects. METHODS: Two hundred patients with PD were enrolled in our study. All subjects met DSM-IV criteria for PD or PD with agoraphobia (PDA). All patients were assigned to receive SSRI monotherapy for 12 months with either citalopram (n = 50), fluoxetine (n = 50), fluvoxamine (n = 50), or paroxetine (n = 50) in a randomized, nonblinded fashion. Both the treating psychiatrist and the patients were not blind to the assigned treatment, but the clinician raters were blind to the study medication. The study design allowed for assignment of a particular SSRI as indicated according to the clinical judgment of the study psychiatrists. The Panic Self-Questionnaire, which is a self-report scale, was administered at baseline and then once per month during the duration of the 12-month study. The visual analog scale and the Clinical Global Impression Scale were administered at baseline and then once per month during the period of the study. Reports of sexual dysfunction were assessed using a nonstructured clinical interview at monthly visits. The body weight of study subjects was measured at baseline, and then at the 12th month visit end point. RESULTS: Of 200 patients who entered the study, 127 patients (63.5%) completed the full 12-month protocol. Retention rates were highest for paroxetine (76% [38/50]), intermediate for citalopram (68% [34/50]) and fluvoxamine (60% [30/50]), and lowest for fluoxetine (50% [25/50]). Patients who completed the 12-month protocol responded favorably to the study treatment. The paroxetine and the citalopram groups had significantly lower rates of panic symptoms as measured at visits on weeks 4 and 8. At visits on months 3, 6, 9, and 12, however, there were no statistically significant differences between the 4 groups in relapse rates (defined as the occurrence of 1 or more panic attacks during the previous week of treatment) (F1,127 = 0.17; P = 0.13 [not statistically significant]). At the 12th month end point, patients in all 4 treatment groups had a statistically significant increase in body weight. Body weight among the study population increased by 6.1 + 4.9 kg from a mean weight of 72.4 + 7.3 kg at the onset of treatment. Reports of sexual adverse effects at the 12th month visit were similar in the citalopram, fluoxetine, and paroxetine groups, but the fluvoxamine patient group reported fewer sexual adverse effects at the 12th month visit. CONCLUSIONS: Most of our PD patients responded well to 12-month treatment with either citalopram, fluoxetine, fluvoxamine, or paroxetine, and the overall response rate was equal after the first 4 weeks of treatment. Although patients treated with paroxetine had the lowest dropout rates during the initiation phase, they had the highest rate of adverse effects as measured at the 12th month visit. Conversely, patients in the fluvoxamine group had the highest dropout rate (which was primarily caused by adverse effects in the initiation phase of treatment.); however, patients who were able to tolerate fluvoxamine throughout the full course of the study were observed to have lower rates of sexual dysfunction and weight gain compared with patients treated with the other agents. Overall, when measured at the 12th month visit, monotherapy with paroxetine and citalopram was associated with a higher rate of sexual adverse effects than was treatment with fluoxetine or fluvoxamine. In addition, monotherapy with paroxetine, citalopram, and fluoxetine seemed to cause more weight gain than did treatment with fluvoxamine.

12-month follow-up study of drug treatment in pathological gamblers: a primary outcome study.

BACKGROUND: Pathological gambling (PG) is a relatively common and highly disabling impulse control disorder. A range of psychotherapeutic agents including selective serotonin reuptake inhibitors, antiepileptic drugs, and opioid antagonists are shown to be effective in the short-term treatment of PG. The use of a wide range of pharmacological treatments for PG is consistent with the observation that PG shares features of obsessive-compulsive spectrum disorders, impulse control disorders, and addictive disorders. The aim of the study is to assess the rate of relapse in treatment-responder pathological gamblers after discontinuation of the active treatment. METHODS: Our study sample was composed of 43 male pathological gamblers who had been full responders to 1 of 4 drug treatment regimens (fluvoxamine, topiramate, bupropion SR, or naltrexone) from several previous acute open-label (12-week) comparison studies. Full response was defined as the absence of gambling for a 1-month duration together with improvement on the Clinical Global Improvement scale. The 43 full responders were then followed prospectively for an additional 9 months, which included a 3-month open-label continuation phase and a 6-month medication-free follow-up phase. Follow-up visits were performed on a monthly basis throughout the duration of study. At every follow-up visit, a comprehensive psychiatric diagnostic evaluation was performed on all patients, and patients were assessed for symptoms of gambling using a self-report instrument and collateral family reports. The Clinical Global Impression Improvement scale was also administered at every follow-up visit. Raters were blind to the previous drug treatment. RESULTS: Most patients did not relapse during the 6-month medication-free follow-up phase. Three of 6 patients with fluvoxamine, 3 of 9 with topiramate, 7 of 18 with bupropion SR, and 4 of 10 with naltrexone relapsed. Relapse was strictly defined as gambling behavior at any time during the 6-month medication-free follow-up period. Most of the patients did not gamble during the follow-up period, and the patients that did gamble reported a decrease in gambling losses. CONCLUSIONS: This naturalistic long-term follow-up outcome study demonstrates that among pathological gamblers who respond to a 6-month trial of medication, most patients seem to maintain full-response during a 6-month medication-free follow-up phase. Further studies are needed to confirm our findings.