Page 895 - Cardiac Nursing

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C HAPTER 38 / Obesity: An Overview of Assessment and Treatment 871
metabolism of lipids and glucose, but is not yet approved by et al. found that individuals who took sibutramine and partici-
FDA. 111 Numerous drugs that work through different mecha- pated in a 30-session lifestyle modification program lost 12.1 kg
nisms, originally developed for other indications, are undergoing after 1 year compared with a 5.0-kg weight loss for those who only
clinical trial evaluation. These include bupropion, a reuptake in- took sibutramine. 92 People who lose weight during the initial 6
hibitor of norepinephrine, serotonin, and dopamine; topiramate months of drug therapy and maintain that loss without side ef-
and zonisamide, antiepileptic agents; and metformin, exenatide, fects may be considered successful and maintained on the drug
and pramlintide, antidiabetic agents. Each of these drugs has been with periodic follow-up to provide reinforcement and to monitor
associated with small weight losses when used in the treatment of progress, side effects, weight, blood pressure, and laboratory val-
disorders for which they are indicated. 111 However, the pharma- ues. Currently, FDA approval is for a 2-year course of treatment.
cological agents currently approved for the treatment of obesity
are limited. Bariatric Surgery
Two medications have long-term approval. Sibutramine acts Morbid obesity is considered a major health problem with related
centrally to block the reuptake of serotonin and noradrenaline, economic consequences. Health care costs associated with obesity
thereby reducing food intake and increasing thermogenesis. 110 A are in excess of $117 billion annually in the United States. 121
10-mg daily dose of this drug has been shown to produce modest Bariatric surgery is now recognized as a viable treatment option
weight loss in several clinical trials, but its use is associated with for those with morbid obesity or those at high risk for obesity-re-
increases in heart rate of approximately 4 to 6 beats per minute lated mortality or comorbidities. 121,122 In 2004, there was an
and increases of about 2 to 4 mm Hg in systolic and diastolic 800% increase in the number of bariatric surgeries in the United
blood pressure. 112 Therefore, sibutramine must be used cautiously States, increasing from 13,386 in 1998 to 121,055 in 2004. 123
in persons with hypertension, stroke, and cardiovascular dis- These numbers have also increased world wide from 40,000 pro-
ease. 111 A second drug, orlistat, acts peripherally in the gastroin- cedures in 1998 to 146,301 procedures in 2003. 124 Criteria es-
testinal tract to inhibit gastric and pancreatic lipases essential for tablished during the 1991 NIH consensus conference for bariatric
2
digestion of fats, thereby decreasing fat absorption by approxi- surgery, which includes a BMI 40 kg/m or a BMI of 35.0 to
2
mately 30%. 113 It is also associated with decreased absorption of 39.9 kg/m and a concomitant morbidity such as sleep apnea, un-
fat-soluble vitamins A, D, E, and K. 111 Orlistat requires a thrice controlled diabetes, cardiovascular disease, or weight-related prob-
daily 120-mg dosing with meals and adherence to a low-fat diet lems interfering with daily functioning are still reasonable today. 52
to prevent significant gastrointestinal side effects, including oily or There are numerous bariatric surgical procedures that include
loose stools and fecal incontinence. Therefore, patient adherence gastric bypass, gastric banding, and gastroplasty. Buchwald and
to the diet and medication must be monitored. A half strength Williams 124 reported the relative percentages of the most com-
formulation of orlistat is now available as the over-the-counter mon procedures worldwide are: gastric bypass (65.11%), gastric
medication, Alli from GlaxoSmithKline. A meta-analysis reported banding (24.41%), vertical banded gastroplasty (5.43%), and the
that average 1-year weight losses relative to placebo were 4.5 and less frequently performed biliopancreatic diversion/duodenal
2.9 kg for sibutramine and orlistat, respectively. 114 switch (4.85%). The Roux-en-Y technique is the preferred ap-
Rimonabant, a drug under investigation for weight loss treat- proach to gastric bypass. It involves the construction of a gastric
ment, blocks the CB 1 cannabinoid receptors in the ECS. The pouch of approximately 20 to 30 mL capacity that is attached to
ECS contributes to the control of energy homeostasis, and ECS a Y-shaped limb of small bowel of different lengths. The proximal
overstimulation is linked to obesity. 115 CB 1 receptors were found stomach is separated from the remaining part of the stomach with
to mediate the actions of marijuana and its appetite-stimulating staples. Today, more than 90% of the gastric bypass surgeries are
effect. 116 A cannabinoid antagonist, rimonabant blocks the CB 1 performed laparoscopically. 122,125 The gastric banding procedure
receptors in the central nervous system, gastrointestinal tract, and is also done laparoscopically and involves placing a band around
adipose tissue that promote increased food intake. 110 the upper part of the stomach approximately 1 to 2 cm below the
Large randomized clinical trials comparing rimonabant to gastroesophageal junction, forming a 30 mL gastric pouch. 125
placebo found that rimonabant produced significantly greater dose- The vertical banded gastroplasty involves partitioning the stom-
dependent weight losses after 1 year. 117 The 20-mg dose also yielded ach with four parallel rows of sutures and applying a band at the
significantly greater decreases in waist circumference and triglyc- opening between the upper gastric pouch and the body of the
erides and insulin resistance with increases in HDL-cholesterol com- stomach. The biliopancreatic diversion involves removing three
pared with placebo. 118 However, rimonabant has been associated quarters of the stomach, preserving the pylorus, and constructing
with depressive symptoms, and persons taking the 20-mg dose were an ileoduodenostomy distal to the pylorus. The alimentary and
2.5 times more likely to stop taking the drug due to depressive mood biliopancreatic limbs have approximately the same length. In all
disorders compared with those taking the placebo. 119 As a result of of the procedures, vomiting is a common problem. Patients un-
increased attention to the psychiatric side effects of new medications dergoing gastric restrictive procedures have an increased risk of
such as rimonabant, the FDA has required that drug companies now experiencing dumping syndrome and nutritional deficiencies
include a comprehensive assessment of suicide risk during the course (particularly vitamin B 12 , calcium, and iron). 122,125 The key com-
of clinical trials. 120 plications associated with bariatric surgery include pulmonary em-
When medications are prescribed for weight loss, it is most bolus, respiratory failure, stomal obstruction or stenosis, bleeding,
likely that long-term use will be needed because obese individuals and gastrointestinal leaks from the breakdown of a staple/
who lose weight using pharmacotherapy usually experience weight suture line. The level of risk depends upon the patient’s age, BMI,
regain after the treatment is stopped. 112 For the total benefits of surgical procedure used, and the presence of other comorbidities. 122
drug therapy to be realized, medication use needs to be accompa- Substantial weight loss can result from these surgical proce-
nied by a program of behavior modification, a structured eating dures. Indeed, these patients also had either reversal or significant
plan, and increased physical activity. 112 For example, Wadden improvement in type 2 diabetes, hyperlipidemia, hypertension,