Childhood Obesity in the United Kingdom 97use [81]. Although noradrenergic agents are widely used in the USA for the
treatment of obesity in adults, in Europe, they remain unavailable.
Serotonin-Receptor Agonist
Lorascerin
Lorascerin is another obesity drug approved by the FDA. It acts as an
agonist at serotonin receptors (5-HT2C) within the propiomelanocortin neurons
of the hypothalamus. This results in decreased food intake and increased
feelings of satiety. Importantly, Lorascerin is highly selective for the 5-HT2C
receptor, with very little activation of 5-HT2A or 5-HT2B receptors. This is
significant, since activation of the 5-HT2A receptor has been associated with
neuropsychiatric effects, and activation of the 5-HT2B receptor can cause
valvulopathy and pulmonary hypertension [85].
Lorascerin has been tested in two Phase 3 clinical trials, BLOOM [86] and
BLOSSOM [87]. In the BLOOM trial, participants either received lorascerin
10mg twice a day or a placebo pill for 52 weeks, alongside diet and exercise
interventions. After 52 weeks of treatment the average weight loss in the
Lorascerin group was 5.8%, compared to 2.2% in the placebo treated group.
Furthermore, the researchers were also able to show significant improvements
in markers of cardiovascular risk [86]. In the BLOSSOM trial, 22.6% of
participants receiving Lorascerin 10mg twice daily achieved a weight loss of
at least 10%, compared to 9.7% of patients in the placebo group [87]. In both
trials, echocardiography showed no increase in valvulopathy in those
undergoing treatment with Lorascerin compared to those in the placebo group.
Side effects noted from these trials include headache, dizziness and nausea
[88].
Combination Therapy
Phentermine/Topiramate
A combination therapy of Phentermine and Topiramate, (Phen/TPM) was
approved by the FDA in July 2012 for patients aged 16 years and over and
subsequently became available in the USA in September 2012 [89]. This
combined therapy consists of immediate release Phentermine and delayed-
release Topiramate in a capsule, and has been shown to result in an average
12.2kg weight loss over 52-104 weeks, in three different clinical trials [90, 91,
92]. The idea is that combining these drugs allows smaller doses of each drug