INTRODUCTION
As an efficacious selective serotonin reuptake inhibitor (SSRI)
paroxetine is widely used for the treatment of numerous psychiatric
disorders including generalized anxiety disorder, post-traumatic stress
disorder, depression, obsessive-compulsive disorder and panic disorder
among others.1 Among other groups of antidepressants; SSRIs,
SNRIs and mirtazapine are more likely to cause hyponatremia in older
adults. 2
Paroxetine has been shown to be more effective in the treatment of
depression with least anticholinergic adverse effects compared to
tricyclic antidepressants (TCA). 3 The pharmacokinetics of
paroxetine differ widely among different individual groups; conclusively
slower elimination has been noted in the elderly with increased plasma
concentrations. It has an elimination half-life of 21 hours and a
variable dosing duration that is dependent upon indication. 1
The mechanism of SSRIs which causes hyponatremia is believed to be
concomitant to that of the development of syndrome of inappropriate
antidiuretic hormone secretion (SIADH). The groups of population at a
higher risk for developing hyponatremia with SSRIs involve the people
with lower serum sodium concentrations, the elderly, female gender and
reduced body weight. 4
It has been established that there is a major link between treatment
with SSRIs and hospitalizations due to hyponatremia. However, this risk
decreases when TCAs or mirtazapine is used. 5 Antidepressants
shown not to cause hyponatremia include; amoxapine, dosulepine,
doxepine, trimipramine, iproniazide. 6
Despite the effectiveness of paroxetine, a significant link to its
chronic use (about 10 years) and hyponatremia has not yet been
established. Studies have been conducted and have shown to indicate
incidence of hyponatremia in elderly patients taking antidepressants,
nevertheless; there is a lack of evidence linking the chronic use of
SSRIs with hyponatremia in middle age group people.