To clarify the efficacy of antiobesity drugs, this article reviews all long-term (> or =36 weeks), placebo-controlled trials of obesity pharmacotherapy published since 1960. Since fears of anorexiant-induced heart valve damage preclude many physicians and patients from even considering antiobesity drugs, this area is also reviewed in-depth. Electronic database and manual bibliography search was used to identify all relevant publications. While existing studies are too few and heterogeneous to warrant meta-analysis, their review does provide evidence highly relevant to the safety and efficacy of available anorexiants. Weight loss attributable to obesity pharmacotherapy (ie, in excess of placebo) in trials lasting 36 to 52 weeks was 8.1% or 7.9 kg for those receiving phentermine resin, 5.0 % or 4.3 kg for those receiving sibutramine hydrochloride, 3.4% or 3.4 kg for those receiving orlistat, and -1.5% or -1.5 kg for those receiving diethylpropion hydrochloride. Physiologic, pathologic, and epidemiological studies strongly support that anorexiant-induced valvulopathy is attributable to specific serotonergic properties of the fenfluramines that are not present with available weight loss drugs.
From this study: Glazer G. Long-term pharmacotherapy of obesity 2000: a review of efficacy and safety.
Arch Intern Med. 2001 Aug 13-27;161(15):1814-24.
Phentermine has been shown to cause a 5-15% weight loss if given daily or intermittently. Compared with sibutramine and orlistat, phentermine is cheaper, and specific formulations allow once-daily administration. However, phentermine is indicated only for short-term treatment, and tolerance often develops. Common adverse effects associated with phentermine are dry mouth, insomnia, increased blood pressure, and constipation.
From: Campbell ML, Mathys ML. Related Articles
Pharmacologic options for the treatment of obesity. Am J Health Syst Pharm. 2001 Jul 15;58(14):1301-8.
Phentermine does seem to help with weight loss. It helps even more when combined with fenfluramine (now withdrawn) or fluoxetine (ie Prozac). However, when combined with these drugs the neurotoxicity is increased (both to serotonin and dopamine neurons). Phentermine on its own results in some dopamine nuerotoxicity. How much compared to amphetamines I don't know -- probably slightly less. Personally, I'd rather take an amphetamine for weight loss (also it's probably easier to obtain).
