QsymiaŽ (Phentermine / -Topiramate Extended Release)
A New Hope in Diet Drug Therapy
The drug manufacturer Vivus Inc has been successful in obtaining registration of a new drug which has been demonstrated to be effective in supporting weight loss, namely QsymiaŽ (previously known as QnexaŽ). The testing of this medication has lasted several years, and the tests and Vivus's application to have it registered have been watched with great interest during this time. The United States is delighted, as this is the first diet medicine for some years to have shown to have significant results.
QsymiaŽ acts by suppressing the appetite, so that the people taking it feel less hungry and thus find it easier to eat less. This is important for obese patients, who have learned to stop listening to the signals from their bodies, and continue eating even when their stomachs are full. They thus find it easier to comply with a sensible eating plan. QsymiaŽ is strictly speaking not an entirely new medication. It consists of a specific combination of two already-known medicines. One of these has been used as an appetite suppressant for some years: it is phentermine, marketed as Adipex. The other is new to the field of obesity treatment: it is topiramate, with the trade name Topamax. This has for some time been used to treat people with convulsions, usually caused by epilepsy. It appears that when topiramate is combined with phentermine, in specific doses and in specific formulations, that the combined effect of these two agents is an enhanced degree of appetite suppression.
The data garnered during the clinical trials showed that QsymiaŽ was much more effective than the other drugs on the market in assisting patients to lose body mass. The FDA, the Federal Drug Administration, states that a weight loss medication should help at least a third of the people using it to lose at least 5% of their body mass: QsymiaŽ did better than that, helping people to lose between 10% and 15% in a year.
It could be asked why it would be necessary to register a whole new agent, when the two active ingredients are already registered for use, are available in the market, and in use. The answer relates to two aspects. One is that topiramate is not registered for use in weight loss, and therefore may not be prescribed for this application until such registration is granted by the FDA. The other is that it is not just a matter of prescribing some of each and then getting the patient to take them correctly. QsymiaŽ has a particular formulation. It will be available in three strengths, and in each the two active ingredients are combined in specific dose formulations. The mildest strength will contain 3.75 mg of phentermine and 23 mg of topiramate, the intermediate strength 7.5 mg of phentermine and 46 mg of topiramate, and the full strength 15 mg of phentermine and 92 mg of topiramate. In addition, the bioavailability of the two active ingredients is very important: the phentermine will be present in an immediate-release compound and the topiramate in a slow-release compound. This special combination of doses and activity is important for the medication to produce the clinical results that are required.
The other good news about QsymiaŽ is that it appears to be good for the patient in other ways. It reduces blood pressure, which is very helpful as most overweight people suffer from a raised blood pressure. In fact, a raised blood pressure results in many of the health conditions which lead to early mortality in obese people, namely heart failure and strokes. In addition, QsymiaŽ relieves sleep apnea, which is the condition where patients stop breathing effectively during sleep: they may snore excessively, or their breathing stops temporarily, resulting in the patients awakening feeling tired. By relieving sleep apnea, QsymiaŽ helps people get a good night's rest so that they feel and function better the next day. Another beneficial effect is that it lowers cholesterol: a raised cholesterol is another health challenge that obese people struggle with.
The Food and Drug Administration (FDA) is the body which controls the types of medication which may be prescribed in the US. In this way the FDA protects the health of the nation. Any new medication, whether entirely new or a new way of combining existing medications, has to be approved by the FDA for the use of specific conditions. Thus the FDA had to grant approval for the use of QsymiaŽ in the treatment of obesity, as in spite of the fact that phentermine had been registered for this use for some time, topiramate had not. So the FDA undertook a very thorough study of both the efficacy of QsymiaŽ and the safety with which it could be used. The types of side effects, the incidence of those side effects in the patients using them, and the seriousness of those side effects when they occur, are all factors that the FDA studies.
The first time that Vivus Inc made an application for registration for QsymiaŽ, the FDA rejected the application. It was satisfied that QsymiaŽ is effective for the purpose for which the registration was required, but it was concerned about certain of the side effects, and required further investigation of these. So the company performed extensive additional testing, and re-submitted its application, which has just recently been approved. So now the nation's obese have this additional medication available to them, and they can use it with the knowledge that it is safe for most people, and that the side effects are not life-threatening.
Most of the patients who report side effects experienced some nausea, a dry mouth, an altered sense of taste, or some diarrhea or constipation. A few people have headaches or fatigue. It seems that a few patients develop an increased susceptibility to respiratory infections. These side-effects were experienced in mild forms. What was more worrying was that there seemed to be, in the first clinical trials, an increased incidence of depression, suicidal ideations, and other psychiatric conditions. During the second clinical trials these were found not to have any significant link with the use of QsymiaŽ. What has been established, regarding serious side effects, is that pregnant women should not take it, as their babies are more likely to be born with a cleft palate. As this is the only section of the population that is at risk of a serious complication, the FDA decided to agree to register QsymiaŽ with the proviso that pregnant women are not to take it.
In view of the fact that QsymiaŽ reduces blood pressure, instead of raising it as most other diet drugs do, it is generally regarded as mainly safer than the other existing treatments for obesity. It is very effective in helping people lose weight and its side effects are of such a mild nature, and are only experienced in a few subjects that they could be regarded as a small price to pay for an effective medication.
With the FDA approval for the registration of QsymiaŽ to be prescribed in the management of obesity, medical practitioners have another tool to use against this physical condition which holds so many threats to health and to life. The definition of obesity varies, but it is generally taken to mean a body mass index of 30 or more.
Of course, any weight loss programme cannot depend on medication alone, but must include a sensible eating plan and also an appropriate exercise regime. However, many overweight people find that they need the help provided by appetite suppressants, particularly at the start of the programme: it seems that some people's appetites are so active that getting started on a sensible eating plan is just not possible for them without an appetite suppressant.
As the FDA registration was approved in the middle of July 2012, Vivus Inc now needs to organise production of the medication. It will take time for there to be sufficient of the medication available for distribution to the many drug stores which will stock it, so the public needs to be a little patient. But once it is available it is expected that large numbers of people will flock to their doctors for a prescription.
Because of the nature of QsymiaŽ the FDA has decided that, like many other medicines which should only be used under the supervision of a doctor, that it will only be available on prescription. People will not be able to buy it over the counter. Also, because QsymiaŽ consists of a combination of active agents, the risks associated with drug-drug interactions or allergic reactions are increased: after all, many obese patients are already taking various medicines for their health problems. It is safer for a medical practitioner to advise the patient on drug safety in such instances, and to watch the patient for potentially dangerous side effects.
Obesity has so many negative implications for people's health that a new medication which has been shown to confer such positive results, is to be welcomed with enthusiasm.