Abstract
The results of the 2007–2008 National Health Survey reveal that more than 61.4% of Australians are either overweight or obese [1]. This has led to a renewed focus on strategies to control body weight with significant government investment in such ventures. Patients with psychiatric illnesses warranting antipsychotic medication appear doubly disadvantaged. A recent study showed that 78.8% of patients receiving such medication increased their body weight by 7% [2]. Obesity is a known harbinger of adverse health outcomes. People with severe mental illness die up to three decades earlier than the general population. A recent survey suggests that obesity-related problems cost Australia an estimated $58.2 billion annually in direct and indirect costs [3]. While the mainstay of obesity treatment was centred on diet modification and exercise, diet pills have gained popularity in recent years. The diet pill industry in Australia is estimated to be worth $208 million per annum, out of which $27 million is attributed to Duromine sales alone [4].
Phentermine associated mood and psychotic problems have been reported since the late 1960s. A literature search by these authors revealed only five case reports with psychosis or mood symptoms attributed to phentermine use [5]. We report a series of four patients who have developed psychotic symptoms while on treatment with Duromine. We believe that this will become an increasingly more common occurrence given the current preoccupation with weight-related problems and discuss implications for psychiatric practice.
Ms A, a 30 year old Caucasian woman with a history of bipolar affective disorder suffered several relapses of manic psychosis following the ingestion of phentermine. Depressive episodes would be characterized by poor self-image and increasing pre-occupation with weight prompting visits to her general practitioner with requests for diet pills. During the last episode she had been on 40 mg of Duromine for six days following which she suffered a manic relapse as evidenced by hallucinations, pressured speech and argumentative behaviour. Symptoms abated following the discontinuation of Duromine.
Ms B, a 30 year old Caucasian woman with a family history of affective illness and no prior psychiatric history developed paranoid delusions one week following the use of Duromine. She continued to use Duromine over the next 12 months with a gradual worsening of her paranoia culminating in her first psychiatric admission to hospital. Family were able to corroborate the temporal correlation of psychosis with the initiation of Duromine treatment. A rapid resolution of symptoms was reported on discontinuation of Duromine and commencement of antipsychotic medication. Over the following five years she has continued to receive treatment for psychosis suggesting a schizophrenia-like illness uncovered by the use of Duromine.
Mr C, a 52 year old Caucasian man with no prior psychiatric history self-medicated with Duromine (30 mg) bought on the streets for symptoms of lethargy. He was also on treatment with methadone for chronic back pain. He described auditory hallucinations and delusions of reference two weeks after commencing Duromine. His symptoms resolved with the cessation of Duromine but he continues to report depressive symptoms four years later.
Ms D, a 39 year old aboriginal woman reported paranoid delusions (referential, being bugged, persecution) and auditory hallucinations after using Duromine (60–90 mg/day) over a 6-day period. There was a past history of post natal depression and one prior episode of drug-induced psychosis on cannabis. Akin to case 3 her use of Duromine had not been prompted by weight concerns but more for recreational purposes.
Phentermine is no safer than other diet pills (mephentramine, fenfluramine) that have already been withdrawn from the Australian market and is as likely to precipitate psychosis as other synthetic amphetamine analogues. While a direct causative link between phentermine and psychosis is still debated there appears to be little doubt that phentermine may unmask an underlying vulnerability to affective and psychotic illnesses [5,6]. Phentermine is also fast emerging as a substance of abuse, further raising the spectre that Duromine-precipitated psychosis will be more commonly encountered in psychiatric practice.
We recommend a renewed educational effort to raise awareness about the risks associated with Duromine prescription with a view to addressing the trend in increased prescription despite the clearly articulated risks in product literature. Corollaries to this would include a more stringent history-taking to elicit increased vulnerability to the psychiatric side effects of Duromine. Prescription should also be associated with close monitoring of mental state and a low threshold of suspicion for Duromine precipitated psychosis. Recommendations for obesity-related interventions clearly state the primacy of diet modification and exercise as first line interventions, and the use of pharmacotherapy only where obesity presents a clear and direct threat to the patient's health. These principles need to be reflected in resource allocation in public health policy.