Depression is related to a deficiency in the amount or function of serotonin, norepinephrine and dopamine in the brain. The need for a wide range of antidepressants with different pharmacological profiles, is driven by the diversity of clinical manifestations seen during depressive episodes [1].
Selective Serotonin Reuptake Inhibitors (SSRIs) are considered as first line treatment in depression, with Selective Serotonin Noradrenaline Reuptake Inhibitors (SSNRIs) prescribed in patients, where SSRIs are ineffective [1].
SSRIs have a single function, whereby they increase the levels of serotonin in the brain by limiting its reabsorption, though some SSRIs do show a weak affinity for norepinephrine and dopamine [1].
SSNRIs, increase serotonin and norepinephrine throughout the brain, as well as increasing dopamine in the prefrontal cortex [2].
In addition to their use in depression, SSRIs and SSNRIs are also effective in the treatment of [1] [3]:
The market data below (see Figure 1), focuses mainly on the N06A5 class (SSNRIs) and the shifts in market share as a result of the launch of Duloxetine O in 2004. There were significant macroeconomic changes in the pharmaceutical industry during (and before) its launch.
At the time of its launch, the SSNRI market consisted of two products; Duloxetine O and Venlafaxine O, which was launched in the mid-1990s. The first venlafaxine generic was launched in 2006, followed by another six venlafaxine generics (Venlafaxine G) between 2009 – 2012. The launch of the first duloxetine generic (clone – Duloxetine C) was in 2009, followed by a single generic (Duloxetine G) in 2013.
Depression is a common but serious mood disorder that affects a person’s behaviour, feelings, thoughts and sense of well-being [4]. Nearly 1:3 South Africans will suffer from a mental disorder in his/her lifetime.
The burden of mental disorders has grown over the past 20 years (1990 – 2010), with major depressive disorder rising in the Top 25 ‘Causes of Disability’ rankings from 15th to 11th over the period [5], with a lifetime prevalence of 9.8 % [6][7].
There is still a treatment gap of 75%, with only 25% of people with common mental disorders receiving treatment of any kind [8].
This rise is expected to last, partly due to the ongoing epidemiological transition from communicable to non-communicable diseases, and co-morbidities between HIV and chronic health conditions [6]. Major depressive disorder is also comorbid with a variety of psychiatric conditions [9].
At the time of this report, depression was not yet a Prescribed Minimum Benefit (PMB), and minimal benefits are allocated to depression (including Major Depressive Disorder).
In 2004, Bipolar Disorder was listed as a PMB. Thus, patients with Major Depressive Disorder (subtly different from Bipolar Disorder II) are sometimes classified as Bipolar II, in order to be able to access chronic medicines.
