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Suggest Dosage Of Lithium When 150 Mg ER Preparation Is Not Available
Question: I need to take 150 mg of lithium total each day. The 150 mg dose is no longer made as an extended/controlled release version. I contacted several pharmacies, including ani, the current maker of lithobid, whose predecessor used to make a 150 er, to learn this. No current company makes 150 er.
So, given my choices are limited, can I split a 300 er daily, or would it be safer to take an intact 300 er every other day? Right now taking a 150 mg non-er capsule or tablet is not an option because I couldn't get a new prescription for it for 3 months. Also, if splitting the 300 er is not safe and I can cut it evenly, I would like to know why this is so. By my logic, and experience with other coated er tablets, all it does is revert the pill to its pre-er state.
I did discover that the real difference in half life in er versus is 12 hours (er) versus 8 hours (non-er). Sounds like er is some fancy marketing to me.
This has proved to be a difficult question so please pass on it if you do not know the answer. I will ask for a refund if I get answer that isn't really a concrete, actionable, answer. If you choose to answer, this forms a contract between us which, if broken, will entitle me to a full refund. Be aware I have a copy with this original language, which may be redacted (removed) if your answer allows me to act on the information given. I believe it may take some research but given at this point I don't even know the cost and have potentially wasted the time to write to you, I believe my expectations can be as high as if I were asking a million dollar question. Next time, post your price ahead of wasting the patient's time, which may be more valuable than yours.
So, given my choices are limited, can I split a 300 er daily, or would it be safer to take an intact 300 er every other day? Right now taking a 150 mg non-er capsule or tablet is not an option because I couldn't get a new prescription for it for 3 months. Also, if splitting the 300 er is not safe and I can cut it evenly, I would like to know why this is so. By my logic, and experience with other coated er tablets, all it does is revert the pill to its pre-er state.
I did discover that the real difference in half life in er versus is 12 hours (er) versus 8 hours (non-er). Sounds like er is some fancy marketing to me.
This has proved to be a difficult question so please pass on it if you do not know the answer. I will ask for a refund if I get answer that isn't really a concrete, actionable, answer. If you choose to answer, this forms a contract between us which, if broken, will entitle me to a full refund. Be aware I have a copy with this original language, which may be redacted (removed) if your answer allows me to act on the information given. I believe it may take some research but given at this point I don't even know the cost and have potentially wasted the time to write to you, I believe my expectations can be as high as if I were asking a million dollar question. Next time, post your price ahead of wasting the patient's time, which may be more valuable than yours.
Brief Answer:
Splitting it will be a good option
Detailed Answer:
Hello XXXXXXX
Thanks for technical question.
Before giving you specific answer, I would like to mention some points for your information.
You are right that 150 mg ER preparation of lithium is not available.Even 150 mg plain tablet use is also reduced.The reason behind it small "Therapeutic Window" of Lithium.
It means lithium will be effective only when its serum level is within some range. Below the minimum recommended level it has no therapeutic effect and above the recommended level chances of side effects increase.
Therapeutic lithium levels: 0.4 to 1.0 mmol/L (may vary from laboratory to laboratory). 150 mg is likely not able to achieve therapeutic level.
So it is not going to be useful.
Now coming to your specific question.
You want to take 150 mg daily dose. You have 300 mg er preparation only.
Taking it alternate day will not be effective considering its half life. Though it is extended release preparation it can not be extended up to second day. So on second day you would not have any lithium in actual in your blood/serum.
Splitting the er preparation is going to make dose half and preparation will be like plain medicine. You already in need of 150 mg. So splitting of the er preparation will fulfill your need of 150 mg. There is no increase in dose than recommended, so no safety issue is there.
Er preparation is made to slow the release of molecule in blood , maintain it serum level ,avoid frequent dosing and reduce side effects. Splitting the er molecule is harmful when dose is large and half life is long. Splitting makes the higher dose immediately available to the blood and can cause adverse reaction. It is not the case with you.
Hope I have answered your query satisfactorily.
Regards,
Dr.Chintan Solanki.
Splitting it will be a good option
Detailed Answer:
Hello XXXXXXX
Thanks for technical question.
Before giving you specific answer, I would like to mention some points for your information.
You are right that 150 mg ER preparation of lithium is not available.Even 150 mg plain tablet use is also reduced.The reason behind it small "Therapeutic Window" of Lithium.
It means lithium will be effective only when its serum level is within some range. Below the minimum recommended level it has no therapeutic effect and above the recommended level chances of side effects increase.
Therapeutic lithium levels: 0.4 to 1.0 mmol/L (may vary from laboratory to laboratory). 150 mg is likely not able to achieve therapeutic level.
So it is not going to be useful.
Now coming to your specific question.
You want to take 150 mg daily dose. You have 300 mg er preparation only.
Taking it alternate day will not be effective considering its half life. Though it is extended release preparation it can not be extended up to second day. So on second day you would not have any lithium in actual in your blood/serum.
Splitting the er preparation is going to make dose half and preparation will be like plain medicine. You already in need of 150 mg. So splitting of the er preparation will fulfill your need of 150 mg. There is no increase in dose than recommended, so no safety issue is there.
Er preparation is made to slow the release of molecule in blood , maintain it serum level ,avoid frequent dosing and reduce side effects. Splitting the er molecule is harmful when dose is large and half life is long. Splitting makes the higher dose immediately available to the blood and can cause adverse reaction. It is not the case with you.
Hope I have answered your query satisfactorily.
Regards,
Dr.Chintan Solanki.
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Above answer was peer-reviewed by :
Dr. Shanthi.E
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