For FDA information about regular Seroquel (immediate-release formulation), see http://www.drugs.com...te-tablets.html
Dosage Forms and Strengths
25 mg tablets
50 mg tablets
100 mg tablets
150 mg tablets
200 mg tablets
300 mg tablets
400 mg tablets
The immediate-release form is often taken twice a day.
For FDA information about Seroquel XR (extended-release formulation), see http://www.drugs.com...eroquel-xr.html
Dosage Forms and Strengths
50 mg extended-release tablets
150 mg extended-release tablets
200 mg extended-release tablets
300 mg extended-release tablets
400 mg extended-release tablets
Switching Patients from SEROQUEL Tablets to Seroquel XR Tablets
Patients who are currently being treated with SEROQUEL (immediate release formulation) may be switched to Seroquel XR at the equivalent total daily dose taken once daily. Individual dosage adjustments may be necessary.
Acute withdrawal symptoms, such as insomnia, nausea and vomiting have been described after abrupt cessation of atypical antipsychotic drugs, including quetiapine fumarate. In short-term placebo-controlled, monotherapy clinical trials with Seroquel XR that included a discontinuation phase which evaluated discontinuation symptoms, the aggregated incidence of patients experiencing one or more discontinuation symptoms after abrupt cessation was 12.1% (241/1993) for Seroquel XR and 6.7% (71/1065) for placebo. The incidence of the individual adverse events (i.e., insomnia, nausea, headache, diarrhea, vomiting, dizziness and irritability) did not exceed 5.3% in any treatment group and usually resolved after 1 week post-discontinuation. Gradual withdrawal is advised.
....Elimination of quetiapine is mainly via hepatic metabolism. The mean-terminal half-life is approximately 7 hours for quetiapine and approximately 12 hours for norquetiapine within the clinical dose range. Steady-state concentrations are expected to be achieved within two days of dosing. Seroquel XR is unlikely to interfere with the metabolism of drugs metabolized by cytochrome P450 enzymes.
Reduce by 10% per month to start
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...
Tapering the extended-release form (Seroquel XR)
Since the lowest XR dosage available is 50mg, 50mg will be the smallest decrease you can make. If your starting dosage is 400mg or more, reducing by 50mg at a time may be tolerable for a few rounds.
Splitting an extended-release tablet appears possible (there are many reports on the Web of people doing this), but this compromises the extended-release quality, possibly resulting in immediate-release quetiapine. If you are used to the extended-release form, you may be sensitive to the "dosage dumping" resulting from immediate release of the drug.
The extended-release quality of Seroquel XR is due to a "matrix" formulation, not the coating on the tablet. From http://www.touchpsyc.../pdf/riedel.pdf
Pharmaceutical Formulation and Chemical Structure
Quetiapine XR is available as quetiapine hemifumarate....All tablets are film-coated. The drug has the same chemical structure as quetiapine immediate-release (quetiapine IR). The galenic structure of quetiapine XR involves a polymeric gel matrix of hydroxypropylmethylcellulose (HPMC). Quetiapine is interlinked with the polymeric structure of HPMC in a net-like structure. HPMC widens its structure in the presence of water to form a smaller hard core and a softer outer cellulose gel membrane. Thus, the tablet can release the active drug continuously over a period of 20 hours.
You cannot make a liquid from quetiapine XR, the matrix formulation clumps into a gel (as it does with Pristiq).
For more precise tapering, you may wish to take part of your dose in the immediate-release form, which comes in a 25mg dosage that you can cut up, and from which you can make a liquid (see below). (Generally, when you mix two types of tablets, for insurance coverage the prescription will need to be written for divided doses.)
You can cut up the 25mg immediate-release tablet in quarters or halves, enabling you to taper by 6.25mg or 12.5mg at a time. When you reach a daily dosage of 60mg, you may wish to use a liquid form to maintain a 10% rate of taper based on the last dosage.
Note that if you cut up quetiapine XR or switch your entire dose from the extended-release form to the immediate-release form, you may need to take a half-dose twice a day or make other dosage adjustments up or down according to your reactions.
Get a liquid compounded by a pharmacy
With a prescription, you can go to a compounding pharmacy to have a liquid made from immediate-release quetiapine, or custom capsules from quetiapine XR if necessary (the capsules probably will be more like the immediate-release form of the drug, as breaking the XR tablet may compromise the extended-release matrix).
See our topic on compounding pharmacies.
Make your own liquid with water
Immediate-release Seroquel is moderately soluble in water http://www.drugbank.ca/drugs/DB01224
According to http://www.elmmb.nhs...36=34585&char=Q NHS UK advice for people who cannot take tablets:
- Tablets not soluble, may try to crush and dissolve in warm water.
- For oral use mix crushed tablet with yoghurt as it has a bitter taste.
According to http://www.new.ijpi....s/2011/07/6.pdf
Formulation and In Vitro Evaluation of PH-Independent Sustained Release Drug Delivery System of Quetiapine Fumarate
HT Mulani, I Parmar, NJ Shah 2011
3.2. pH dependent stability of drug Drug solution was prepared with the concentration 300 ppm in 0.1 N HCl, 4.5 aceaate buffer, pH 6.8 phosphate buffer and 7.4 phosphate buffer; and observed for 24 hrs at predetermined time intervals. Drug is stable at pH range from 1.2 to 7.4 and showed the maximum 2 % degradation as compared to initial concentration (Table 2).
So it's most likely stable mixed with water for 24 hours.
Use a combination of tablets or capsules and liquid
Rather than switch directly to an all-liquid dose, you may wish to take part of your dose in liquid and part in lower-dose tablets or capsules, gradually converting to all liquid as you get to lower dosages. This can be very convenient and reduce any problems switching from one form of the drug to another.
For example, you may wish to take a 50mg Seroquel XR tablet and the rest in liquid for your daily dose. As the liquid is made from immediate-release quetiapine, you may wish to take it later in the day -- see notes above for regular Seroquel.
If your doctor prescribes compounded liquid and tablets or capsules at the same time, most likely he or she will have to indicate "divided doses" in the prescriptions to get the drugs covered by insurance.
Edited by Altostrata, 10 June 2015 - 11:27 AM.