Mysimba is an anti-obesity drug composed of two components mainly 7.2 mg naltrexone (the anti-addiction drug) and 78 mg bupropion (the antidepressant drug). Mysimba is a diet pill which has been developed by Orexigen and has been licensed by European Union. It is also known as Contrave as approved by the FDA in the US whereas Mysimba is the brand name for the European market. It mainly affects the brain and central nervous system working particularly their regulation in appetite.
CLINICAL TRIALS & EFFECTIVENESS OF MYSIMBA:
The effectiveness of Mysimba has been seen in four different studies including 4,500 obese and overweight patients. These patients were given Mysimba with proper counselling, diet and exercise. The main aim of the study was to check the notable reduction in body weight at least 5% over 28 or 56 week of treatment. There were also some patients who achieved 10% weight loss surprisingly. The results are as follows:
- Patients with 5% weight loss ranged from 28 to 42%.
- 22% of the patients achieved 10% weight loss.
- In another study 36-40 % patients achieved collectively 5 and 10% weight loss.
Apart from weight loss Mysimba is also associated with a number of benefits i.e. less waist circumference, reduced visceral fat and most importantly reduction in LDL form of cholesterol and triglyceride. Lastly in diabetic patients reduced glycemic control was also observed.
RISK FACTORS ASSOCIATED:
Although there are no severe side effects seen during the clinical trials of Mysimba but some of the adverse side effects of the drug are due to the components bupropion and naltrexone.
- As already mentioned above bupropion is an antidepressant and contains some active substances which act to increase the suicidal behavior in people with age less than 25 years, though no such suicide attempts were noted in the clinical trials.
- Bupropion is also associated with the risk of seizure. 2 out of 3,239 patients experienced seizures during trials. Mysimba should not be given to patients who have an early history of seizure.
- Some anaphylactic reactions with bupropion have been reported during clinical trials. Treatment should be stopped if there are symptoms of fever, rash, pain in joints and muscle, swelling of throat, tongue, lips or face. 1 in 10 patients have experienced allergic reactions.
- It is also associated with disturbed blood pressure and hypertension. Almost 1 in 4 patients taking the drug had an increase in their blood pressure.
- In case of excessive doses such as 300 mg/day it can cause hepatocellular injury.
- Hepatic impairment.
- Renal impairment.
- Neuropsychiatric symptoms.
- Vomiting: it is one of the most common side effect of Mysimba and 1 in 10 patients suffer from it.
- Muscular pain
- Concentration disturbance
RISK MANAGEMENT PLAN (SRK):
Although Mysimba is not prescribed yet but it has been approved by committee for medicinal products for human use (CHMP). They found it significant for clinical use although its effectiveness in weight loss was less. There were some concerns regarding its safety measures but on a whole its benefits were found to be more as compared to its risks that why it got approved by the CHMP. The RMP plan also gives the necessary measures to be taken in account to fortify that Mysimba is safely used.
DOSAGE AND USE:
- It can only be taken with a prescription.
- A single tablet should be taken in the start of the treatment in the morning and then slowly increase to two after 4 weeks.
- Preferably taken with food.
- In case of any side effect, treatment should be stopped.
- There should be an initial loss of 5% body weight in the first 4 months, if not then the treatment should be stopped.
MECHANISM OF ACTION (NALTREXONE & BUPROPION):
Naltrexone is an opioid receptor antagonist and make sweet things taste less pleasant. While bupropion is a dopamine or norepinephrine inhibitor which increases the level of dopamine neurotransmitter in the brain reducing appetite. In combination both drugs affect two regions in the brain firstly, nucleus of hypothalamus which is involved in the food intake and energy balance. Secondly, the mesolimbic dopaminergic reward system that is involved in the processing of food stimuli and its rewarding aspects and also influence eating behavior. In this way it helps to maintain calorie-controlled diet and to reduce body weight.
Obesity is one of the most emerging issues worldwide and a challenge to health which ultimately leads to some chronic diseases including cardiovascular disease, diabetes blood pressure, stoke, cancer and other diseases. In other words, obesity is the root to all diseases. Especially in Europe according to World Health Organization (WHO) over 50% of the men and women are overweight and 20% of men and 23% of women are obese. As the ratio of obesity has raised the past few years so it has become necessary to control it. With the advancement of technology in pharmaceuticals discovery and development people are trending more and more towards the weight loss drugs or supplements rather than adopting healthy practices.
HISTORICAL TREATMENTS FOR OBESITY:
Obesity has always been in subject from ancient times. The earliest weight loss drugs to be used were emetics and cathartics. Emetics included honey water and hellebore plants advised to be taken two to three times a month for both men and women. On the other hand, cathartics contained sea spurge, bindweed and Canadian berry.
–The drug is approved and launched in US not prescribed yet, and should be use under doctor’s supervision with proper diet and exercise.
– The drug is to be used in obese people with BMI of 30 or more and in overweight people with BMI between 27 and 30.
Putting the debate in a nutshell, Mysimba other than its side effects do have certain benefits which cannot be ignored and yet there are chances of its rapid usage in the coming years.