Phyllocontin

i was just wondering what the ususal dosage is for this drug and what the maximum dosage is, the only reason i am asking as i trying to find a dose at which gives me theraptic level

thanks

katie xxx

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Hi Katie,

The BNF maximum dose of standard Phyllocontin is 450mg twice a day, although many consultants will prescribe higher doses for people who are having difficulty getting therapeutic levels on the standard dose. There is also a stronger preparation, Phyllocontin Forte, which can be given up to 700mg twice a day - this is intended for smokers and other people who may metabolise theophylline faster than usual.

There are lots of different things that affect theophylline levels in the body. The drug is given as a twelve hour modified release preparation - which means that the tablet is specially prepared to sit in your gut for twelve hours and dissolve slowly, releasing the drug gradually. Certain gut problems can affect the way this happens and thus reduce the absorption of the drug.

Metabolism of the drug can also be affected. Other drugs can slow down or speed up the metabolism of theophylline - the most common ones to cause problems are antibiotics such as erythromycin, which can slow down metabolism and thus increase the risk of getting toxic side effects. Some people also have a genetic predisposition to rapid metabolism of theophylline - people with this gene mutation will often be unable to get good theophylline levels even on high doses. However, this is very rare, and problems with levels are much more likely to be caused by other issues such as absorption and interactions with other drugs.

The problem is that all this things can have a variable and unpredictable effect on theophylline absorption and metabolism, so it is often not possible just to whack up the dose of theophylline until the levels are therapeutic, as this risks toxicity if there is a change in the way your body deals with the drug. Theophylline toxicity can occur at doses only a little higher than the therapeutic dose, and it is very unpleasant, and can be dangerous. That is why doctors are often quite cautious when increasing the dose.

Hope this helps

Em H

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Hi Katie,

I have struggled to find a dose of phyllocontin which gives me a therapeutic dose, I am currently on 800mg twice a day and am lucky if I get a level of 5 with this. However, my team are reluctant (as am I) to increase the dose further as it appears my problem is absorption based and therefore the potential to become toxic is something I have to be aware of. We have found that if I do not eat then my levels do significantly improve - however this is not something that is recommended for a healthy lifestlye. I am now having IV top ups every 6 wks to try and keep things more stable

Some people have found that splitting the total amount of phyllocontin taken into three dosages has given some benefit. However, it is very much an individual thing and something that you and your docs will have to work on over a few months (or longer). It took a long time for me to get to the dose that i am on (over a year if I remember correctly) but I remember the feeling of frustration that accompanied the many blood tests and increasing dosages.

Rusty

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thanks for that info i am currently on 450 mg twice a day and have to go back for blood test next week to se if that increase from 450mgh and 225 mg a day has helped.... and correct me if i am wrong but theraptuic levels are between 8 -16 but they aim for 10 ish?

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