Posted by ed_uk2010 on January 5, 2015, at 2:37:21
In reply to Re: lithium dosing question (controlled release) » Mogger, posted by SLS on December 30, 2014, at 20:27:44
Hi,
>I am 1.0 at 1500 mgs. My question is how variant can doses be with lithium? Meaning do you think I might be able to get away with 900 mg at one point as my blood level was at .6 when I got a blood test at 900?
>Hoping that there can be an effective range below 1.0.
I think there will be. Maintaining a level of 1.0 is uncommon beyond the first few months of treatment, in any condition. This level is mainly used for stabilisation when acutely unwell. Levels of 0.7 to 0.8 are common for maintenance in bipolar I disorder, with 0.8 being common for those with a history of severe mania. 0.6-0.7 is more usual for those with a history of mainly hypomania eg. bipolar II disorder. 0.4-0.6 is common for maintenance in predominantly depressed pts with no recent mania or hypomanic episodes. Around ~ 0.4 is not uncommon for maintenance in unipolar depression, as an augmenting agent. As an aside, it is no longer common practice to aim for more than 1.0 in any condition, including acute mania - where 0.8-1.0 is preferable. Lithium is rarely the drug of first choice for stabilisation of acute mania these days, antipsychotics and Depakote are more popular for this purpose.... with lithium being a common combination strategy.... and a useful maintenance drug. Lithium monotherapy is too slow to reliably control acute mania on its own, and levels above 1.0 have been generally replaced by the use of additional medication such as Depakote and APs.
Maintaining levels above 0.7 on a long term basis is probably best avoided after stability has been achieved unless it's clear than lower levels are ineffective - which is most likely when there is a history of severe manic episodes. Such levels may be poorly tolerated in the long-term, particularly with respect to kidney function. Thyroid dysfunction is common in the long term and requires monitoring - symptoms may be confused with a relapse.
After several years of use (or shorter if 'acute phase' blood levels are maintained), a gradual deterioration in kidney function is common. Since lithium is excreted almost entirely via the kidneys, a decrease in dose is often possible over time. Elderly people who've taken Li for years often have very low maintenance dose.
>I see maintenance doses of lithium are around 900-1200mgs. I am 1.0 at 1500 mgs
>I see maintenance doses of lithium are around 900-1200mgs. I am 1.0 at 1500 mg.If I were you I'd probably want to reduce 1200mg now, with a target level of 0.8. After several months, if you are well, I would consider taking around 1000mg (exact dose depending on brand), with a target level of ~0.7. If still well after several more months, I would want to look at reducing to around 900mg. Over the next year or so, 900mg might permit a level of 0.6-0.7, with is usually satisfactory for those with no history of mania - and could be ideal for you in several months time, maybe a year - I suggest 1200mg for now. Given your particularly good response to a high dose, I suspect that aiming for 0.4-0.5 would be too low for you; this sort of range is more appropriate for maintenance/augmentation in unipolar depression in those who find high doses unpleasant and mood flattening.
In practice, doses up to a maximum of ~900mg are the norm for long-term maintenance, some need as little as 300mg (but almost certainly not you!), and occasionally less in the elderly. . 1200-1500mg is generally used in the acute phase only (and never in the elderly), with ~1000mg-1200mg being relatively uncommon in the long term (beyond the subacute phase) even in young people.... such doses were only common for the maintenance of bipolar disorder many years ago when lithium was more likely to be used as monotherapy due to fewer options being available for combination. Doses given in manufacturer's product literature are often misleading and out-of-date.
>Halving tablets.
It depends on the brand. All modified-release lithium tablets which can be broken into two equal halves have a score line down the middle. These tablets are designed to be halved without damaging the modified release mechanism. Obviously, the should not be crushed. In the UK, the brands Priadel MR and Camcolit MR can be halved, for example. This is very useful because it allows adjustments in steps as small as 100mg ie. half a 200mg Priadel tablet. I see that Eskalith CR 450mg tablets are scored, but I don't know about other brands which are not available here.
>Dosage interval
Lithium is generally given twice a day in the acute phase and once or twice a day for maintenance.
Alternate day dosing or different doses on alternate days is normally used only in patients who have a long half-life due to impaired kidney function. The fact that you require 1500mg (a lot) to produce a level of 1.0 suggests very good kidney function, and probably a half-life at the lower end of the range. Those with poor kidney function would reach 1.0 on a much lower dose.
Hope this helps.
poster:ed_uk2010
thread:1074533
URL: http://www.dr-bob.org/babble/20150102/msgs/1074806.html