Posted by Cam W. on June 3, 2001, at 19:37:33
In reply to Re: Lamictal -another question! » Cam W., posted by chloe on June 3, 2001, at 18:24:42
• Chloe - The half-life of Lamictal is approximately 33 hours when you first start taking it. The half-life does decrease by about 26% once a steady state (when the amount taken just offsets the amount excreted by the body) after about 14 days, to approximately 26 hours Its rate of absorption is slowed by food, but the extent to which it is absorbed is not, with peak levels occurring 1.4 to 4.8 hours. Lamictal's absolute bioavailability (the amount of drug absorbed and available for mood stabilizing/anticonvulsant activity) is about 98%, which is high compared to other drugs. It is metabolized (hydrolyzed) by the liver.
At the 12.5mg and 6.25mg dosage every 3 to 4 days you probably won't get much of a therapeutic effect, but your body should start adjusting to the side effects. It may take longer to reach a therapeutic effect (ie two months, instead of one), but the lessening of side effects, especially if you are sensitive to them, may make the wait worth it. This slower titration would probably not be adviseable if you were using the Lamictal as an anticonvulsant, but may be appropriate for people who are using it for mood stabilization (and bipolar depression) and are sensitive to its side effects. Do follow your doctor's advice, though. You both need to stay on the same page for treatment therapy, and he/she knows your condition much better than I could.
• Briana - The Lamictal monograph states that a normal starting regimen is 25mg to 50mg daily for two weeks and increasing by 25mg or 50mg every two weeks. Clinically, I find that when used as an adjunct for mood stabilization that taking 25mg for a week or two, then raising it by 25 mg every week or two, seems to work the best and avoids rashes. I should add that, if taken with valproic acid (Depakene™) or divalproex (Epival™ or Depakote™), the dose of Lamictal should be halved because these drugs interfere with Lamictal's metabolism.
As for the rash, yes it is a concern, but not as big a concern as once thought. The Stevens-Johnson life-threatening rash is "usually" seen in children under 12 years, who are titrated too fast. It is the inclusion of children in the statistics that gives a value of 1 in 100 (children have a risk of S-J rash of about 1 in 50). Still, in adults, 1 in 10 get some sort of rash, especially if the dose is increased too fast. This would freak me out if I was taking the drug and one should contact their doctor immediately if they do notice a rash. Chances are it is not S-J, but I wouldn't risk it. We have had a few people who have developed a rash with quick titration, but when rechallenged at a lower dose and increased that dose slower, these people were able to remain on Lamictal, with no return of rash.
So, yes the rash is important to watch for during the initial titration phase of the drug, but if a person does develop a rash, I would say follow the doctor's orders. A doctor must be comfortable with trying a rechallenge with Lamictal, at least until some more scientific study into this area is done.
I hope these answers are of some use to both of you. - Cam
poster:Cam W.
thread:64875
URL: http://www.dr-bob.org/babble/20010530/msgs/65282.html