Prescription Weight Loss Medications

Obesity has reached epidemic proportions in the U.S. According to researchers, over 50% of Americans are trying to lose weight (Nicklas, Huskey, Davis, & Wee, 2012, p. 481). Researchers also found that obese adults were more likely to be successful achieving weight loss if they combined prescription weight loss medications with a comprehensive diet program like Weight Watchers (Nicklas et al., 2012, p. 481). However, all prescription weight loss medications do not function in the same way, nor do they have the same results for every patient. Nurses also play an important role in monitoring pharmacotherapy in obese patients by aiding in the early detection of side effects, as well as providing general medical care to patients.

Obese patients frequently try various weight loss methods. The “first-line” of treatment for these patients is exercise and maintaining a healthy lifestyle (Heal, Gosden, & Smith, 2013, p. 107). However, for many patients, pharmacotherapy is also warranted (Heal et al., 2013, p. 107). In the United States, central nervous system (CNS) drugs are commonly used to treat obesity (Heal et al., 2013, p. 107). Among the popular drugs are “phentermine, d-amphetamine, ethamphetamine, benzphetamine, phendimetrazine and diethylpropion” (Heal et al., 2013, p. 107). Each drug has a different mode of action, resulting in varied levels of effectiveness for obese patients.

Weight loss drugs have varying degrees of popularity as well, no doubt owed to their presumed effectiveness. According to Heal et al. (2013), the most prescribed weight loss drug in the United States is phentermine (trade name, “Ionamin” or “Duromine”) (p. 111). Phentermine is administered in 15-30 mg doses, and is a noradrenaline and dopamine releasing agent (Kennett & Clifton, 2010, p. 65, 71). While patients using phentermine may experience side effects such as dry mouth and insomnia, researchers found that use of the medication did not substantially increase systolic blood pressure (SBP), or diastolic blood pressure (DBP) (Heal et al., 2013, p. 111). These patients may still be monitored for increases in SBP or DBP during follow up visits.

In addition to phentermine, there are another CNS drugs commonly used for weight loss. Another popular prescription medication is diethylpropion (trade name, “Tenuate” or “Apis”) (Heal et al., 2013, p. 108). Administered in doses of 75 mg, diethylpropion is a sympathomimetic, or appetite suppressant (“Appetite Suppressants”, 2011). Other medications in this class are phendimetraz and benzphetam (Heal et al., 2013, p. 108). These medications affect the neurotransmitters in the brain, making patients feel generally less hungry than they would without taking the medicine (“Appetite Suppressants”, 2011). However, use of diethylpropion is only indicated for a short period of time -- generally a few weeks -- and patients should not use this drug for longer periods of time (“Appetite Suppressants”, 2011). Unlike, phentermine, the use of diethylpropion may result in increased blood pressure (“Appetite Suppressants”, 2011). Patients using this medication should be monitored for changes in SBP or DBP during follow up visits. As diethylpropion may also be habit-forming, patients should also be closely monitored for any signs of chemical dependency (“Appetite Suppressants”, 2011). This drug, like any other, requires regular follow up with a treating physician.

Another class of medicine is also frequently used for weight loss in obese patients. The prescription drug orlistat (trade name, “Xenical”), is administered in 360 mg doses, and is a lipase inhibitor (Heal et al., 2013, p. 107; Kennett & Clifton, 2010, p. 63). Orlistat is notably the only FDA-approved “peripherally acting anti-obesity drug” (Heal et al., 2013, p. 107). However, patients using orlistat are cautioned against prolonged use of the medication, because it may interfere with the patient’s absorption of other medications, as well as the patient’s general absorption of nutrients from food (Kennett & Clifton, 2010, p. 63). These patients, particularly those taking other medications, should be monitored carefully during follow up visits for evidence of this phenomenon. Regular blood tests/screening may be indicated as well.

While many weight loss drugs have proven to be effective, others drugs are no longer available in the market because of health-related concerns. Most recently, rimonabant and sibutramine were withdrawn from the United States (Heal et al, 2013, p. 107). Researchers found that just 20 mg per day of rimonabant increased the “risk of psychiatric adverse events – i.e., depressed mood disorders and anxiety” in patients (Després, Gaal, Pi-Sunyer, & Scheen, 2008, p. 555). The U.S. Food and Drug Administration also found that patients taking rimonabant were at increased risk for suicide (Després et al., 2008, p. 555). Similarly, sibutramine (trade mark, “Meridia”) was withdrawn from the U.S. amid reports that the drug increased the risk of heart attack and stroke in patients, resulting from an increase in heart rate and blood pressure (DeNoon, 2010). The removal of these drugs follows a long line of other controversial weight loss drugs, such as fenfluramine and d-fenfluramine (Heal et al, 2013, p. 108). Patients taking these two medications together (as prescribed) were at significant risk for “primary pulmonary hypertension and cardiac valvulopathy” (Heal et al, 2013, p. 108). Researchers opine that, given the current climate surrounding weight loss drugs, it may become increasingly difficult to register new prescription drugs with the FDA (Heal et al., 2013, p. 108). However, this has not stopped some pharmaceutical and biotech companies from trying to do just that.

Three new anti-obesity medications are on the horizon. Bupropion/naltrexo (trade name, “Contrave”), topiramate/phentermine (trade name, “Qnexa”) and lorcase (trade name, “Lorqess”) are all in varying pre-registration phases with the FDA (Heal et al., 2013, p. 108-109). In light of the cardiovascular concerns surrounding sibutramine, Contrave is required to undergo a

long-term cardiovascular outcome trial to demonstrate that the medication is safe for use and does not pose a cardiac risk (Heal et al, 2013, p. 109). The drug will be re-submitted to the NDA sometime during 2014 (Heal et al., 2013, p. 109). Similar to Contrave, Qnexa is conducting lengthy inquiry into whether there are any connections between the use of this medication and birth defects in children (Heal et al., 2013, p. 109). Lastly, Lorqess remains under consideration, despite the possible connection between the medicine and tumors in patients (Heal et al., 2013, p. 109). There are challenges to introducing new drugs into the U.S. However, given the comprehensive review process of these medications, they should be safe to use and, hopefully, effective in aiding weight loss.

While weight loss medications may have adverse effects on patients, they may also aid obese patients in losing weight. Nurses may assist in the administration of these drugs by carefully monitoring patients for possible side-effects. Nurses may also collect information on other prescription medicines that the patient is taking, to avoid any possible drug interactions. Lastly, nursing staff may provide quality medical care to patients, ensuring that patients receive the follow up treatment required.

References

Appetite suppressants (sympathomimetics) for obesity. (2011, April 1). WebMD. Retrieved from http://www.webmd.com/diet/phentermine-for-obesity

DeNoon, D. (2010, October 8). Weight loss drug Meridia off the market at FDA's request. WebMD. Retrieved from http://www.webmd.com/diet/news/20101008/fda-rejects-weight-loss-drug-meridia

Després, J., Gaal, L. V., Pi-Sunyer, X., & Scheen, A. (2008). Efficacy and safety of the weight-loss drug rimonabant. The Lancet, 371(9612), 555.

Heal, D.J., J. Gosden, and S.L. Smith. (2013). A review of late-stage CNS drug candidates for the treatment of obesity. International Journal of Obesity 37: 107-117. Print.

Kennett, G.A., & Clifton, P.G. (2010) New approaches to the pharmacological treatment of obesity: Can they break through the efficacy barrier? Pharmacology Biochemistry and Behavior 97(1): 63-83. Print.

Nicklas, J. M., Huskey, K. W., Davis, R. B., & Wee, C. C. (2012) Successful weight loss among obese U.S. adults. American Journal of Preventative Medicine 42(5): 481-485. Print.