As with other psychiatric drugs, do not taper Invega by taking a dose every other day! This causes a fluctuating level of the drug in your nervous system and can make you very sick.
To minimize the risk of withdrawal symptoms, we recommend a conservative taper of 10% from the previous dosage every few weeks. The amount of the decrease keeps getting smaller. Some people find they can go faster and some people find they have to go slower -- they can only tolerate decreases of a fraction of a milligram at a time. See Why taper by 10% of my dosage?
Very careful tapering is necessary when you have had psychotic symptoms. Such symptoms can appear as withdrawal symptoms; that will cause you to become diagnosed as relapsed and re-medicated. Read Psychiatrist: Some patients are better off without antipsychotics...
from Invega official FDA Information
INVEGA® Extended-Release Tablets are available in the following strengths and colors: 1.5 mg (orange-brown), 3 mg (white), 6 mg (beige), and 9 mg (pink).
Invega is also administered as an injection, Invega Sustenna http://www.drugs.com...-sustenna.html:
Recommended initiation of INVEGA® SUSTENNA® is with a dose of 234 mg on treatment day 1 and 156 mg one week later, both administered in the deltoid muscle. The recommended monthly maintenance dose is 117 mg; however, based on previous clinical history of tolerability and/or efficacy, some patients may benefit from lower or higher maintenance doses within the additional available strengths (39 mg, 78 mg, 156 mg, and 234 mg). Following the second dose, monthly maintenance doses can be administered in either the deltoid or gluteal muscle.
Adjustment of the maintenance dose may be made monthly. When making dose adjustments, the prolonged-release characteristics of INVEGA® SUSTENNA® should be considered [see Clinical Pharmacology (12.3)], as the full effect of the dose adjustment may not be evident for several months.
Tapering off Invega extended-release tablets
The range of dosages available in the tablets suggests one might step down using a combination of tablets. For example, to taper from 12 mg/day, one might get a prescription filled for 9mg and 1.5mg tablets, for a reduction to 10.5mg/day.
The extended-release characteristic is in the shell of the tablets. According to the manufacturer http://www.invega.co...tic-medications
INVEGA® releases its medicine over a 24-hour period. As the tablet passes through your body, it gives off the medicine at a constant rate.
The medicine in the INVEGA® tablet is contained in a nonabsorbable shell. This shell will leave your body in your stool. If you see the shell, do not worry. This is normal.
Without a shell, the half-life of the basic drug, paliperidone, in Invega appears to be 20-24 hours at a dose of 1mg http://dmd.aspetjour....expansion.html
I don't know anyone who's tapered by cutting up Invega tablets. If you've done this, please post in this topic.
To taper from small amounts of Invega, one might switch to risperidone liquid.
Taper by switching to risperidone liquid
Paliperidone is a close relative of risperidone, being it is an active metabolite of risperidone, according to http://www.drugs.com...isperidone.html
Titrating a liquid is very good for very small measured decreases in dosage, allowing more precise measurements.
from Risperdal Official FDA Information
Risperdal® Oral Solution can be administered directly from the calibrated pipette, or can be mixed with a beverage prior to administration. Risperdal® Oral Solution is compatible in the following beverages: water, coffee, orange juice, and low-fat milk; it is NOT compatible with either cola or tea.
If you want to do this, be sure to read Tips for tapering off Risperdal (risperidone)
Injectable Invega Sustenna: Letting it wear off
Invega may be administered via injection every 4 weeks. This form is called Invega Sustenna.
Invega Sustenna is intended to last at "therapeutic" strength for a month, then you would get another injection to keep up the potency. Its half-life is very long -- 25 to 49 days. This means that at 25-49 days, it has worn off to half-strength in your body. It would take about 125-343 days for it to completely leave your body.
The blood level and side effects will be highest shortly after the injection, then wear off somewhat. Given the very long half-life, if you have gotten a single application of Invega Sustenna (often two injections close together), you must let your body gradually metabolize it to go off it.
Switching to tablet form to taper injectable Invega Sustenna
If you get withdrawal symptoms while letting injectable Invega Sustenna wear off, you may need to taper more slowly. Conceivably, one might switch to a lower dosage in the tablet form about a month after the injection; tablets come in a range of dosages that make tapering easier.
See Sec.2.6.1. Table 4 on http://dailymed.nlm....554#section-2.7 for the equivalents of Invega Sustenna (injection) and Invega extended-release tablets.
That page notes
If INVEGA® SUSTENNA® is discontinued, its prolonged-release characteristics must be considered....
If you wish to switch to the tablet form to taper (see below), the following is important http://www.drugs.com...-sustenna.html:
Absorption and Distribution
Due to its extremely low water solubility, paliperidone palmitate dissolves slowly after intramuscular injection before being hydrolyzed to paliperidone and absorbed into the systemic circulation. Following a single intramuscular dose, the plasma concentrations of paliperidone gradually rise to reach maximum plasma concentrations at a median Tmax of 13 days. The release of the drug starts as early as day 1 and lasts for as long as 126 days.
....The release profile and dosing regimen of INVEGA® SUSTENNA® results in sustained therapeutic concentrations....
Metabolism and Elimination
....The median apparent half-life of paliperidone following INVEGA® SUSTENNA® single-dose administration over the dose range of 39 mg – 234 mg ranged from 25 days – 49 days.
Long-Acting Paliperidone Palmitate Injection versus Oral Extended-Release Paliperidone
INVEGA® SUSTENNA® is designed to deliver paliperidone over a monthly period while extended-release oral paliperidone is administered on a daily basis. The initiation regimen for INVEGA® SUSTENNA® (234 mg/156 mg in the deltoid muscle on Day 1/Day 8) was designed to rapidly attain steady-state paliperidone concentrations when initiating therapy without the use of oral supplementation.
In general, overall initiation plasma levels with INVEGA® SUSTENNA® were within the exposure range observed with 6–12 mg extended-release oral paliperidone. The use of the INVEGA® SUSTENNA® initiation regimen allowed patients to stay in this exposure window of 6–12 mg extended-release oral paliperidone even on trough pre-dose days (Day 8 and Day 36). The intersubject variability for paliperidone pharmacokinetics following delivery from INVEGA® SUSTENNA® was lower relative to the variability determined from extended-release oral paliperidone tablets. Because of the difference in median pharmacokinetic profiles between the two products, caution should be exercised when making a direct comparison of their pharmacokinetic properties.
If you are switching from the injection to the extended-release tablets, you need to be careful about the overlap -- you could be taking a high dose if you have recently had an injection and you add tablets. Probably the safest time to make the switch would be at the end of the 4 weeks, when the injection is wearing off.
Gradually lowering dosage of injections
If you need to gradually lower the dosage of the injections to taper off, this can be accomplished by systematically reducing the amount of liquid injected. This requires the cooperation of a doctor.
This is not easy -- the manufacturer, Janssen, intends the dosage to be delivered all at once and supplies only uncalibrated syringes -- they do not have markings on them to measure the contents. Giving 2 injections of different dosages, for example 156mg and 78mg to add up to 234mg, might cause an increased blood level of Sustenna, above that of a single 234mg shot. From an e-mail from the manufacturer posted on the College of Psychiatric and Neurologic Pharmacists (CPNP) site http://cpnp.org/site.../pub_email.pdf
ADMINISTRATION OF 234 MG PALIPERIDONE PALMITATE AS SIMULTANEOUS
156 MG AND 78 MG INJECTION
No systematically collected data is available on using paliperidone palmitate 156 mg plus
paliperidone palmitate 78 mg in place of a paliperidone palmitate 234 mg injection. However,
pharmacokinetic simulations2 show that when paliperidone palmitate 156 mg and paliperidone
palmitate 78 mg are administered as two separate injections on the same day there is an
approximate 15% increase in peak plasma paliperidone concentration and a 9% increase in
trough paliperidone concentration after the first cycle. After two and three cycles of receiving the
156 mg dose and the 78 mg dose as separate injections administered on the same day, patients
will have 11% and 11% higher peak concentrations, respectively, and 8% and 6% higher trough
concentrations, respectively. These simulated increases in plasma paliperidone concentrations
are less than the intra-subject variability seen in clinical trials.
If you were getting 234mg injections, it's possible you might get a 156mg plus a 39mg injection to reduce to 195mg, but I couldn't find any information about this.
Edited by Altostrata, 12 December 2016 - 11:45 PM.