PART 1 is available here:
This part will focus on loading and conversion strategies for haloperidol decanoate.
HOW MUCH MONTHLY MEDICATION IS NEEDED?
Oral haloperidol bioavailability = 65%.
Patient on 10 mg/day haloperidol will have total medication exposure of =
10mg/day X 30 days X 65% = 195 mg/month ~ 200 mg/4 weekly dose.
Source: CNS Spectrums, Volume 22,Supplement S1 (CME SUPPLEMENT)December 2017 , pp. 14-28
HOW TO INITIATE LOADING DOSE ?
(OPTION 1): TWO LOADING DOSE STRATEGY WITH NO ORAL MEDICATION
Loading dose of ~ 20 times the oral maintenance dose in DIVIDED injections during the FIRST TWO WEEKS of conversion to depot medication.
The dose of haloperidol decanoate is gradually reduced, dropping to about ten times the oral dose in the third and fourth months.
No supplemental oral medication was used.
Source: Hosp Community Psychiatry. 1993 Dec;44(12):1155-61.
(OPTION 2): WEEKLY TAPER STRATEGY
Treat with oral haloperidol for 6 weeks and then switch to decanoate.
Haloperidol decanoate 100 mg qweekly X 4 weeks –> q2weekly X 4 weeks –> q4weekly.
During this first 2weeks: Oral Haloperidol coverage of 5 mg/day may be needed during first 2 weeks, as this strategy provided coverage equal to 10 mg/day after the third week.
By the third week, mean plasma haloperidol concentrations from the decanoate injections were comparable with those of the 10-mg oral haloperidol treatment (7.95 +/- 4.94 ng/mL vs. 7.79 +/- 4.79 ng/mL).
Source: J Clin Psychiatry. 1996 Jul;57(7):298-302.
HOW LONG TO CONTINUE ORAL HALOPERIDOL AFTER DECANOATE INJECTION?
At least 1-2 months, as it can take 3 to 5 doses of decanoate before steady state is reached.
Source: Psychopharrnacol 1989; 98:433–439.
I will be thankful if member’s can share their experiences and/or useful articles on these topics of (a) loading dose strategy and (b) length of duration of oral haloperidol after decanoate injection. Thanks.
Dr. Harvinder Singh, M.D. (Admin)
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