86 - Stopping

Stopping

90 The Maudsley® Prescribing Guidelines in Psychiatry CHAPTER 1 Olanzapine long-­acting injection Olanzapine pamoate (embonate, in some countries) is a very poorly water-­soluble salt ester of olanzapine. An aqueous suspension of olanzapine pamoate, when injected deep in the gluteal muscle, affords both prompt and sustained release of olanzapine. Peak plasma levels are seen within 1 week of injection (in most people within 2–4 days)1,2 and efficacy can be demonstrated after only 3 days.3 Only gluteal injection is licensed – deltoid injection is less effective.2 Olanzapine LAI is effective when given every 4 weeks, with 2-­weekly administrations only required when the highest dose is prescribed. Half-­ life is 30 days.1,4 Olanzapine has not been compared with other LAIs in RCTs, but naturalistic data suggest similar effectiveness to paliperidone LAI.5,6 Loading doses are recommended in some dose regimens (Table 1.16). The manufacturer recommends that patients be given oral olanzapine first to assess response and tolerability. Oral supplementation after the first depot injection is not necessary. Switching Direct switching to olanzapine LAI, ideally following an oral trial, is usually ­possible. When switching from another LAI, olanzapine oral or LAI can be started on the day the last LAI was due. Likewise, for switching from oral treatment, a direct switch is possible, but prior antipsychotics are probably best reduced slowly after starting olanzapine. When switching from risperidone Consta, olanzapine should be started, we suggest, 2 weeks after the last Consta injection was due. That is, 4 weeks after the last Consta injection (peak risperidone plasma levels occur 4–5 weeks after the last injection). Stopping Clinicians should consider the gradual release of olanzapine from the pamoate salt when discontinuing treatment. There are various methods of ensuring a linear ­reduction in drug activity.7 Olanzapine may remain detectable in the bloodstream for up to 8 months following the last dose.4 Table 1.16  Dosing regimen for olanzapine. Oral olanzapine (mg/day) Starting dose Maintenance dose (given 8 weeks after the first dose) 210mg every 2 weeks or 405mg every 4 weeks 300mg/4 weeks (or 150mg every 2 weeks) 300mg every 2 weeks 405mg/4 weeks (or 210mg every 2 weeks) 300mg every 2 weeks 300mg every 2 weeks