**1. Introduction**

Obesity and overweight have increasingly become major global health issues. Data from the World Health Organization (WHO) reports a near doubling of the prevalence of obesity worldwide from 1998 to 2008 [1]. In the European Region, an average of over 50% of adults are overweight and nearly 23% obese, with the prevalence of overweight and obesity being highest in Finland (67.1%), Germany (67.2%), the United Kingdom (67.8%), Malta (73.3%), and Greece (77.5%) [2]. Similar alarming trends are seen in the United States NHANES data where 68% of adults have a body mass index (BMI) greater than 25 (overweight or obese) and nearly 37% of the population is considered obese [3-7]. A large burden of health care costs can be attributed to overweight and obesity since multiple disease states such as diabetes, cancer, heart disease can be linked overweight and obesity [8-10]. The WHO estimates that up to 6% of health care expenditures in the European Region, while estimates for the United States have been estimated at 5.7% of the National Health Expenditure [8-11]. Most major organizations, like the WHO, and governmental agencies such as the U.S. Department of Agriculture Center for Nutrition Policy and Promotion have a major focus on the treatment of the obesity epidemic through promotion of proper healthy lifestyle changes [11, 12]. Although multiple anti-obesity agents have progressed through the development process, few drug products have made it through the approval process due to safety or lack of efficacy concerns. Several products, such as amphetamine, fenfluramine and sibutramine, have had their approval removed and/or have been removed from the market following reports linking the drugs to cardiovascular side effects (e.g. hypertension and myocardial infarction), addiction, and death [13-15]. As an alternative, overweight or obese patients may turn to less regulated dietary supplements as a means to assist in weight loss. Multiple herbal products are available that are indicated, often without significant scientific basis, for the treatment of overweight and obesity. The safety and

© 2013 Jordan; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

efficacy of herbal products is often unknown, especially given the presence of multiple chemical compounds, lack of known active constituents or lack of standardization of known compounds [16-19].This chapter presents a review of the chemistry and pharmacology of approved anti-obesity drug products, the proposed mechanism of action for common dietary supplements used in the management of weight loss, and potential drug-drug or herb-drug interactions.

avoided due to an increased risk of hypertension, cardiovascular effects, and changes in blood

CH3 N CH3 CH3

CH3

CH3

O O O

S O O NH2

N N

N

H2C CH3 CH3 CH3 CH3 Cl HCl H2O

Cl

Cl

O H3C H3C

O N

4-oxo-2-oxetanyl] methyl]-dodecyl ester) <sup>O</sup> <sup>O</sup>

Cl

*2.1.2. Phentermine / Phentermine hydrochloride (Fastin®, Ionamin®, Adipex-P®, Suprenza®)*

Phentermine (Figure 1b), a member of the β-phenylethylamine family of compounds, exerts anorectic activity centrally through appetite suppression and is indicated in the short term treatment of obesity in patients with a BMI ≥ 30 kg/m2 [28]. A meta-analysis of six randomized controlled trials of phentermine cumulatively show an added 3.6 kg weight loss over 2 to 24 weeks compared to control groups [29]. Phentermine acts by increasing the release of and inhibiting the reuptake of norepinephrine or dopamine [22]. Although one of the oldest

O

HCl

Interactions with Drugs and Dietary Supplements Used For Weight Loss

http://dx.doi.org/10.5772/51145

109

NH2 HCl

CH3 CH3

O

N

N H

O

N H O H

O

CH2OSO2NH2

O

pressure [27].

(a) Diethylpropion HCl (1-phenyl-2-diethylamino-1-propanone hydrochloride)

isopropylidene-β-D-fructopyranose

(d) Zonisamide (benzo[d]isoxazol-3 ylmethanesulfonamide)

(e) Orlistat ((S)-2-formylamino-4-methylpentanoic acid (S)-1-[[(2S, 3S)-3-hexyl-

(f) Rimonabant (5-(4-chlorophenyl)-1-(2,4 dichloro-phenyl)-4-methyl-*N*- (piperidine-1-yl)-*1H*-pyrazole-3-

carboxamide)

(g) Sibutramine Hydrochloride (cyclobutanemethanamine, 1-(4 chlorophenyl)-N,N-dimethyl--(2 methylpropyl)-,hydrocholoride)

**Figure 1.** Molecular structures of anorectic drugs.

dimethylphenethylamine hydrochloride) CH2C

(b) Phentermine (, , -

sulfamate)

(c) Topiramate (2,3:4,5-Di-*O*-
