12 - Equivalent doses

Equivalent doses

14 The Maudsley® Prescribing Guidelines in Psychiatry CHAPTER 1 Equivalent doses Knowledge of equivalent dosages is useful when switching between FGAs. Estimates of ‘neuroleptic’ or ‘chlorpromazine’ equivalence, in mg/day, between these medications are based on clinical experience, expert panel opinion (using various methods) and any dopamine binding studies available. Table  1.4 provides approximate equivalent doses for FGAs.1–3 The values given should be seen as a rough guide when switching from one FGA to another and are no substitute for clinical titration of the new medication dose against adverse effects and response. Equivalent doses of SGAs may be less clinically relevant, as these medications tend to have better defined, evidence-­based licensed dose ranges. There are several different ways of calculating equivalence based on, for example, defined daily dose,4 minimum effective dose5,6 and average dose.7 These methods give different estimates of equivalence. A very rough guide to equivalent SGA daily dosages is given in Table 1.5.3,6–10 There is considerable disagreement about exact equivalencies, even among the references cited here. Clozapine is not included because this has a distinct initial titration schedule and a high dose–plasma level variability and because it probably has a different mechanism of action. Comparing potencies of FGAs with SGAs introduces yet more uncertainty in respect to dose equivalence. Very approximately, 100mg chlorpromazine is equivalent to 1.5mg risperidone.3 An online calculator is available from the American Association of Psychiatric Pharmacists.11 Table 1.4  Equivalent doses of first-­generation antipsychotic medications. Drug Equivalent dose (consensus) Range of values in literature FGAs – oral Chlorpromazine 100mg/day Reference Flupentixol 3mg/day 2–3mg/day Fluphenazine 2mg/day 1–5mg/day Haloperidol 2mg/day 1.5–5mg/day Pericyazine 10mg/day 10mg/day Perphenazine 10mg/day 5–10mg/day Pimozide 2mg/day 1.33–2mg/day Sulpiride 200mg/day 133–300mg/day Trifluoperazine 5mg/day 2.5–5mg/day Zuclopenthixol 25mg/day 25–60mg/day FGAs – long-­acting injections Flupentixol decanoate 10mg/week 10–20mg/week Fluphenazine decanoate 5mg/week 1–12.5mg/week Haloperidol decanoate 15mg/week 5–25mg/week Zuclopenthixol decanoate 100mg/week 40–100mg/week

Schizophrenia and related psychoses CHAPTER 1 Table 1.5  Second-­generation antipsychotics – approximate equivalent doses.3–10 Drug Approximate equivalent dose SGAs – oral Amisulpride 400mg Aripiprazole 15mg Asenapine 10mg Blonanserin ~ Brexpiprazole 2mg Cariprazine 1.5mg Clotiapine 100mg Iloperidone 12mg Lumateperone 21mg* Lurasidone 80mg (74mg base) Melperone 300mg Molindone 50mg Olanzapine 10mg Pimavaserin 17mg* Quetiapine 400mg Risperidone 4mg Sertindole 10mg* Xanomeline ~ Ziprasidone 80mg SGAs – long-­acting injections Aripiprazole 1-­monthly 300mg/month Aripiprazole lauroxil 441mg every 2 months Olanzapine pamoate 405mg/4 weeks Paliperidone palmitate 100mg/month Risperidone (Consta) 50mg/2 weeks Risperidone (Okedi) 100mg/4 weeks Risperidone (Uzedy) 100mg/month or 200mg every 2 months Transdermal patch Asenapine 5.7mg/24 hr ~ Unknown equivalence at time of writing. * Expert consensus recommendation.