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IN THIS ISSUE:
May 2010

Citalopram and Escitalopram Overdoses
Overdoses with both citalopram (Celexa and others) and escitalopram (Lexapro) can cause serious toxicity.

Borderline Personality Disorder: A Role for Medication?
Antipsychotics, including aripiprazole (Abilify) and olanzapine (Zyprexa), as well as mood stabilizers, such as topiramate (Topamax) and lamotrigine (Lamictal), alleviate some symptoms of borderline personality disorder, but the effects of antidepressants on this condition are variable.

Morphine to Prevent PTSD
Early treatment with morphine following an injury may reduce the risk of posttraumatic stress disorder (PTSD).

Risperidone-Induced Hyperprolactinemia Lowers BMD in Boys
Both risperidone (Risperdal and others), through its effects on prolactin concentrations, and selective serotonin reuptake inhibitors (SSRIs) can lower bone mineral density in boys.

Priapism with Antipsychotics
Antipsychotic medications with a high affinity for the α1-adrenal receptor, such as chlorpromazine (Thorazine), quetiapine (Seroquel), and ziprasidone (Geodon), may be more likely to cause priapism than those with a low affinity.

In Brief
Spouses of People with Dementia Have Higher Risk of Depression; Modafinil (Provigil) Effective for Treating Fatigue in HIV+ Patients

Priapism with Antipsychotics

May 2010

Sometimes occurring as an adverse effect of medication, priapism is a painful, dysfunctional erection of the penis (and, rarely, the clitoris) that represents a urologic emergency and, absent treatment, can lead to lifelong erectile dysfunction. Antipsychotics have been associated with priapism and may cause it by blocking α1-adrenergic receptors. Andersohn and coworkers used the US Adverse Event Reporting System (AERS) database to assess the relationship of antipsychotic-associated priapism with α1-adrenal receptor affinity.1

The authors identified over 400,000 spontaneous reports of adverse drug reactions in males, including 426 cases of priapism. Antipsychotics were deemed the cause in 144 of these cases. The reporting odds ratio (ROR), which measures the disproportionality of adverse reports among different agents, was a markedly elevated 9.9 for antipsychotics with high α1 affinity. High-affinity antipsychotics with a strong "signal" were chlorpromazine (Thorazine), quetiapine (Seroquel), risperidone (Risperdal and others), and ziprasidone (Geodon). A weaker ROR (3.6) was observed for antipsychotics with low or medium α1 affinity. These data are consistent with the scientists' hypothesis that α1 blockade is the mediating factor in antipsychotic-induced priapism. Trazodone (Desyrel and others), a sedating antidepressant, has marked α-antagonist properties and also has been associated with priapism.

A normal erection ends when norepinephrine allows smooth muscle cell contraction and flaccidity. Physiological detumescense appears to be disrupted by α1 blockade. For a patient who requires an antipsychotic drug but has a medical condition like sickle cell disease or a history of dysfunctional erections, which increases the risk of priapism, the authors recommend prescribing a drug with low α1 affinity.

1Andersohn F, Schmedt N, Weinmann S, Willich SN, Garbe E: Priapism associated with antipsychotics: Role of α1 adrenoceptor affinity. J Clin Psychopharmacol 2010;30:68-71.