Generic Olanzapine: Health Authority Opportunity or Nightmare?

A. Aleksander Araszkiewicz; Katarzyna Szabert; Brian Godman; Magdalena Wladysiuk; Corrado Barbui; Alan Haycox

Disclosures

Expert Rev Pharmacoeconomics Outcomes Res. 2008;8(6):549-555. 

In This Article

Results

The notes of 85 outpatients initially prescribed either Zyprexa (38 patients) or a branded generic olanzapine (47 patients) were examined during the study period. Patients prescribed Zyprexa were further broken down into those continually prescribed Zyprexa and those switched to branded generic olanzapine formulations once available. Switching to generic olanzapine occurred almost immediately once it became available in view of the substantial copayment differential. Patient copayments averaged over 87 to 155 zl per pack depending on the strength of olanzapine versus 3.2 zl for the lowest priced branded olanzapine. Each generic olanzapine formulation subsequently had a different shape, color and packaging characteristic to Zyprexa.

The patient characteristics are contained in Table 1 . The differences in the patient numbers, as well as the length of follow-up in the three groups, is explained by the timing of generic olanzapine availability as well as the start date of the study, for example patients on Zyprexa were routinely switched to generic olanzapine once launched in October 2003.

The average length of follow-up was extensive in all groups averaging over 1-4 years ( Table 1 ). Alongside this, no patient prescribed generic olanzapine requested to be switched back to Zyprexa.

The average effective dose of the different olanzapine formulations appeared similar at 18.4 ± 4.96 mg in patients first prescribed Zyprexa and 17.4 ± 9.9 mg in patients first prescribed generic olanzapine. There was also no appreciable change in the dose of generic olanzapine prescribed in the 25 outpatients switched from Zyprexa to generic olanzapine during their extensive follow-up averaging over 2 years. There were also no observable differences in the frequency and intensity of outpatient visits between the three groups.

The clinical characteristics including the number of patients who experienced a recurrence of psychotic symptoms with the various olanzapine formulations are contained in Figure 1.

Figure 1.

Clinical findings for the various olanzapine formulations among 85 outpatients.

There were no unusual side-effects recorded in the patients' notes, either when patients were switched from Zyprexa to generic formulations or prescribed generic olanzapine initially. Only one outpatient relapsed owing to side-effects while on any formulation of olanzapine, in this case Zyprexa.

Overall 41 relapses were recorded among 33 of the 85 outpatients over the period of the substantial follow-up averaging a minimum of 1.21 years (Figure 1). The reasons for the relapses were not reported in the majority of cases. This generally means that the psychiatrists were not sufficiently concerned to record the reasons in the notes (i.e., not due to side-effects or poor compliance but other situations, such as social and life events). The majority of relapses were managed in outpatients (60%). Changing medication was the principal management activity amongst outpatients (68%) followed by dose adjustment or a second antipsychotic added (28%). Among hospitalized patients, there was generally no record on the length of stay. Consequently, there was no opportunity to accurately compute the cost of relapses between the three groups. However, there is no reason to suspect any major differences among the three patient groups.

In the 25 patients initially prescribed Zyprexa before switching, there were a similar number of relapses whilst patients were prescribed Zyprexa and when switched to generic olanzapine ( Table 2 ). No reason was given for the majority of the relapses; poor compliance was stated as the reason in 35% of cases.

There were limited data on discontinuation rates on any olanzapine preparation in the patients' notes. The acquisition cost of olanzapine dropped considerably as different branded generic formulations of olanzapine became available, each competing to be the reference priced compound for reimbursement. Costs to the National Health Fund dropped from approximately 14.64 zl/defined daily dose (DDD) in October 2003 to approximately 8.79 zl/DDD[43] currently (1 September 2008); i.e., a 40% decrease. This decrease is likely to continue with at least five branded generic olanzapine formulations now available in Poland with the possibility of more formulations being launched, matching the situation with risperidone. The cost/DDD for risperidone has fallen by 77% in recent months with 14 branded generics currently available. This represents marginal cost savings with similar intensity of outpatient appointments between the groups as well as a similar number of relapses and their costs.

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