[Phentermine--a "weighty" or a dangerous substance?].

According to international surveys, the appetite suppressant phentermine has frequently been seized although its approval has been withdrawn in Germany. Phentermine is an isomer of methamphetamine though is not optically active such as e. g. amphetamine. The drug acts as a potent substrate at the norepinephrine transporter simultaneously promoting its release; it has a weaker activity at the dopamine transporter whereas its activity towards the serotonin transporter is negligible. Overall, its pharmacological action is comparable to that of amphetamine albeit less strong. Due to its declining effect with time and its addiction potential it has been recommended that phentermine should be used for a few weeks only. Phentermine hydrochloride is a readily soluble salt; absorption of the resinate compound is considerably slower. The drug is not extensively biotransformed; p- and N-hydroxyphentermine are the primary metabolites also being excreted as glucuronide conjugates. Gas chromatographic techniques to identify and to quantify phentermine in biological specimens are applicable following derivatization; however, liquid chromatography coupled to mass spectrometry is currently preferred for analysis of urine, serum or hair. Short-term clinical studies having been performed in the 80s and 90s revealed no serious harmful side effects. However, there are case reports proposing that phentermine usage might be associated with severe health risks due to hypertension, vasoconstriction and vasculopathy; in some individuals, mental illness had been observed. Apart from the legal consequences following purchase of drugs that have been withdrawn its user will simultaneously run serious and unpredictable health risks.