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Brian, Thanks alot for your cogent reply to my question. Aliza is using Sinemet CR 50/200 tablets which she takes in half tablet dosages.Initially,she was taking half a pill every six hours around the clock corresponding to 100/6 mg/hr or 16 2/3 mg/hr of Levadopa and 100mg/day of Carbidopa.We had changed over from using ordinary Sinemet 25/250 (which was causing steep blood pressure drops) to the Sinemet CR which eliminated these blood pressure drops.After about one month of Sinemet CR, Aliza felt her PD symptoms worsening and her neurologist suggested going to five half pills per day.She was not anxious to do this at first,but about two months ago started taking half a pill every five hours corresponding to 100/5 mg/hr or 20mg/hr of Levadopa and 125mg/day of Carbidopa,the upper limit given by Roche for effective protection. Meanwhile,Aliza's symptoms are worsening and she feels off after about 4 hours which suggests going to half a pill every four hours corresponding to 25mg/hr of Levadopa and 150mg/day of Carbidopa which is over the 125mg/day "maximum effective dosage" given by Roche but well within your 300mg/day "maximum safe quantity for effective protection" limit given in your paper.What to do? Your suggestion of juggling 10/100 with 25/100 is feasible. How about alternating 10/100 with 25/100 every four hours? This would keep the Levadopa rate of 25/mg/hr and reduce the Carbidopa rate to 105mg/day in place of 150mg/day. What do you mean by a "safe" quantity? What constitutes unsafe? What do you mean by "effective protection"? What constitutes ineffective protection? Regards. Gil Lieberman --------------------- Date: Mon, 8 Jun 1998 01:54:10 +0000 From: Brian Collins <[log in to unmask]> Subject: Re: Carbidopa On Sun 07 Jun, Gil Lieberman wrote: > Brian, > The March 1998 issue of U.S. Pharmacist has a 16 page insert > by Roche Laboratories,340 King St,Nutley,NJ 07110-1199 entitled > "New Therapeutic Options for Parkinson's Disease"written by > Darrel J.Hulisz,Pharm.D.. > It is stated there that the "maximum effective dosage" of carbidopa > is 100-125mg/day. > In your Living with Levadopa paper,Section 3.5,you give a "safe upper > limit" of 300mg/day. > Is there any contradiction here with regard to the effectiveness of raising > Sinemet dosages? > Gil Lieberman,CG for Aliza,PD,74/3+ Hello Gil - No, I don't think that my and the Roche Laboratories recommendations are in conflict - it is important to be very sure that you have ubderstood the wording. In this case, I will try to extend the descriptions to clarify the meaning. Minimum quantity for effective protection: 75mg of Carbidopa per day. (My number) Maximum quantity for effective protection: 100 - 125mg carbidopa per day (Roche value)- This is their advice on the maximum value to a) do the job effectively with b) no risk of side effects. Maximum safe quantity for effective protection, coupled with acceptably low values of side effects - 300 mg per day. Actually, having extracted myself using 'weasel words', I have to say that putting an upper limit of 125 mg of Carbidopa /day, and a lower limit of 75 mg/day, is imposing an un-necessarily tight limitation on the choice of tablets: Never forget that the most important target is the quantity of LEVODOPA which you need, expressed in mg/hour. Having decided on that value of levodopa, you MUST stay with that value while you sort out the Carbidopa quantity. If you study Table 1, you will see that the only tools available are to juggle Sinemet 10/100 and Sinemet 25/100. (The half quantity Sinemet LS tablets do not seem to be universally available.) My advice is: By all means try to maintain the Carbidopa within 125 mg/day, but don't worry if it creeps up to 300 mg/day, and don't compromise your levodopa quantity. Regards -- Brian Collins <[log in to unmask]> _ .