A Randomized Trial Administering Minocycline, Acetylsalicylic Acid or Pramipexole vs Placebo as add-on to Antipsychotics in Patients With Schizophrenia or Schizoaffective Disorder

Inflammatory processes have been implicated as a cause of schizophrenia (Fan, Goff et al. 2007), and the COX-2 inhibitor, Celecoxib, has been shown to reduce symptoms of schizophrenia (Muller, Krause et al. 2010). Aspirin, which is also a non-steroidal anti-inflammatory drug(NSAID), irreversibly inhibits Cyclooxygenase-1 (COX-1) and modifies the enzymatic activity of Cyclooxygenase-2 (COX-2), thus inhibiting the formation of prostaglandins and reduces inflammatory reaction. In a study funded by the Stanley Medical Research Institute (SMRI) recently published, Laan at all (Laan, Grobbee et al. 2010) administered add-on 1000mg/d of Aspirin to patients with schizophrenia receiving anti-psychotics, and reported reductions in Positive and negative syndrome scale (PANSS) total and PANSS positive scores without substantial side effects.

Minocycline is a second-generation tetracycline that exerts anti-inflammatory and antimicrobial effects while having a distinct neuroprotective profile. Minocycline effects the glutaminergic system, through inhibition of neuronal nitric oxide synthase (nNOS) and blocking of nitric oxide (NO)- induced neurotoxicity (Du et al, 1998; Jiang et al., 2005), and thus has been suggested as a potential treatment for schizophrenia. One published study (Levkovitz, Mendlovich et al. 2010), and another, unpublished study by Bill Deakin found that add-on treatment of 200mg/d of Minocycline was beneficial for symptoms and cognition in schizophrenia, and a study by Miayoka et al (Miyaoka, Yasukawa et al. 2008) administered open-label 450 mg/day Minocycline, and found improvement on positive symptoms.

Indirect pharmacological evidence suggests a relative excess of dopaminergic activity as being implicated in the pathogenesis of some of the symptoms of schizophrenia, and all effective antipsychotics effect dopamine D2 receptors. Pramipexole is a pre-synaptic dopamine auto-receptor agonist hypothesized to improve in symptoms in schizophrenia patients. In an open label study, Kasper at all (Kasper, Barnas et al. 1997) showed statistically significant improvement in PANSS scores in patients not stabilized on haloperidol. Other data indicate that add-on Pramipexole improves symptoms of depression and cognition, in patients with affective disorders (Goldberg, Frye et al. 1999; Sporn, Ghaemi et al. 2000; Goldberg, Burdick et al. 2004; Zarate, Payne et al. 2004), and Malhotra et al, unpublished data.

All of these studies were relatively small, and were performed by investigators with an interest in the compound. The objective of this study is to replicate them in large trial by investigators with no specific interest in the compounds. This proposed study is a multi-arm study, in which patients will be randomized to one of the three study drugs: Pramipexole, Minocycline and Aspirin, or placebo as part of the same protocol. A design by which several active compounds are all compared to the same placebo arm has been utilized before for schizophrenia (Meltzer, Arvanitis et al. 2004). This design has several advantages: in addition to reduced costs and time it exposes fewer patients to placebo, and enables direct comparison between the compounds and not only to the placebo.