General considerations concerning switching antipsychotics

General considerations

1. The goal of this switching table is to offer a guide for physician and pharmacist in switching antipsychotics. The table should be clear, easy to use and contain the most important information. Therefore, the table only contains the most common or special antipsychotics. There is also a group ‘rest AP’, containing antipsychotics with the same switching advice.
2. It should be noted that the table only contains a general advice. Deviant metabolism, comorbidity, the elderly etc. etc. needs tailor-made pharmacotherapy!
3. Because of the risk of acute withdrawal symptoms (e.g. cholinergic rebound) and the risk of relapse, all antipsychotics are gradually tapered.
4. The standard tapering period is approximately two weeks. The two drugs are cross-tapered, reducing and increasing the dose with approximately 25% every 2-3 days.
5. To keep the content simple, dosages are given as percentages as much as possible. Dosages should be rounded to whole or half tablets.
6. All antipsychotics are categorized in short, medium and long, based on their half-life. Depot preparations are categorized as long. It takes approximately 3-5 times the half-life for a drug to reach steady state plasma levels or to be completely eliminated. Switching two antipsychotics with approximately the same half-life are not expected to generate obvious problems. Also switching from a drug with a long half-life to a shorter half-life is in general not expected to give problems, because the new drug will reach steady state plasma levels more quickly.
7. Switching from a drug with a short half life to a drug with a long half life is possibly more problematic. Plasma levels of the first drug decrease rapidly, while the second drug takes longer to reach a steady state plasma level. To overcome possible withdrawal/ relapse, the second drug should be started in a higher dose (approx. 50% of target dose) for about 4 days. Subsequently increase with 25% every 3-4 days.
8. Warnings and advice are limited to the switch only. Specific drug properties can be found via the links on the right.
9. Cytochrome P450 drug interactions between different antipsychotics are checked with the Flockhart interaction table. No inductors or inhibitors were found.
10. Nearly all antipsychotics increase the risk of QT time prolongation with or without Torsade de Pointes (TDP). Under the heading ‘more information’ there is a recommendation, advising ECG monitoring. The SPC of sertindole contains the warning ECG monitoring required. No distinction has been made between drugs with and without TDP.
11. See disclaimer.