Depression is the most mental health disorder disorder among people living with HIV (PLWH) and is predictive of increased HIV-related morbidity and mortality. Treatment of depression in the setting of HIV is challenging as adding antidepressants in combination with combination antiretroviral therapy (cART) increases the pill burden and the potential for drug interactions. Studies have reported HIV medication complexity in patients comorbid with major depression to affect cART adherence. Optimal depression control among PLWH predicts and improves cART adherence and treatment outcomes.
Expert consensus is that selective serotonin-reuptake inhibitors (SSRIs) should be the first-line treatment for depression among PLWH. However, it is unclear whether SSRI therapy is effective in PLWH in low-middle-income countries (LMICs). There is an underrepresentation of LMICs in clinical studies involving PLWH and major depression despite the higher burden of PLWH and depression in LMICs than the high-income countries (HICs).
Fluoxetine is the preferred SSRI and most used for the treatment of depression in LMICs and is approved by their drug regulatory authorities. Fluoxetine is the most evaluated SSRI among PLWH with major depression but with different response rates among various ethnic groups reported. Furthermore, while fluoxetine was the most common SSRI used among the available clinical studies among PLWH, the studies did not report the clinical outcomes related to HIV care and cART.
Dolutegravir (DTG), an integrase strand transfer inhibitor, is the preferred and recommended first-line antiretroviral agent for adults and adolescents with HIV in LMICs. DTG is highly effective in suppressing HIV in both treatment-naive and experienced PLWHs, in addition to a low adverse effect profile and a high genetic barrier to developing drug resistance.
The cytochrome P450 (CYP) enzyme system metabolises fluoxetine, while the major enzyme that metabolises DTG is UGT1A1, with some contribution from CYP3A4/5. Fluoxetine and its major metabolite, norfluoxetine, may inhibit multiple enzymes involved in DTG metabolism, especially during chronic administration. A minor interaction via a membrane transporter mechanism may also be more pronounced with chronic use through the inhibition of the P-gp-mediated transport of DTG by fluoxetine. Patients on DTG report neuropsychiatric adverse events, and there is a relationship between plasma DTG trough concentration, neuropsychiatric adverse events, and UGT1A1 single nucleotide polymorphisms (SNPs). Thus, increases in DTG trough concentrations resulting from drug interaction are a potentially important concern.
Understanding potential drug interactions when fluoxetine and DGT-based cART are co-administered together will assist in optimising the dosing regimen, reducing adverse effects, and improving treatment outcomes among PLWH with major depression. To be able to recommend DTG and fluoxetine concomitant use, a prospective study involving PLWH with major depression is proposed. This study will address key knowledge gaps in drug interactions between fluoxetine and DTG among PLWH with major depression.
