Why do the drug manufacturers recommend the dose regardless of quantity is to be taken once daily. What is the theory in this? Does once daily give you better protection ? Rather than splitting it say three times a day to reduce side effects . ie night/ morning / lunch. In theory splitting it should give a more level coverage.
Thank you mg
Why is any drug dosed in any way? Because that is how it works I guess. Many people take their drugs at night to reduce day time side effects.
Bob, My thinking is that if the drug is designed as a once daily dose then the advice about splitting it from Drs and other medics is wrong. If the design of the drug is to load up the system and taper off then splitting in half does not give the initial required intended loading and because it does not have the intended effect the Drs up the prescription.
Just thinking out loud.
Thanks Mg
Bisoprolol is active in the body for 24hrs, some other beta blockers such as Metoprolol aren't and need to be taken twice a day. Hence Bisoprolol only needs to be taken once daily. This was explained to me by my AF nurse.
Under Consultant advice I take mine twice daily
I felt so unwell after taking the high dose of Bisoprolol 10mg in one go that I split it into two of 5mg morn and night. This made it bearable until it stopped working well after two years and i changed to Nebivolol which I take the same way but in a lower dose.
My EP (cardiologist) doubled my Bisoprolol by prescribing the same dose of 1.25mg to be taken twice daily. I do 9am and 9pm. Works OK for me.
OK, there are several good questions here.
First, I would challenge your statement that a level coverage is always desirable. Sometimes it is, but not always. For instance, some people want low levels of bisoprolol during the night because the HR naturally descends at night, and bisoprolol might lower it too much if taken in the evening.
Sometimes it is a matter of side effects.
Experts on this forum can correct me here, but I seem to remember that a drug has three major elements to consider when deciding how often to take them.
1/ Absorption, how long it takes to get them into the blood stream
2/ Metabolism. For some drugs, how quickly they are metabolised into the therapeutic chemical. For all drugs, how quickly, if at all, they are metabolised into a non-therapeutic form
3/ Excretion. How quickly the drug is eliminated from the blood, and in many cases how quickly the metabolised forms are excreted.
Complicating matters, a drug when metabolised may form two therapeutic forms, each with their own properties. Or the drug itself may be a mixture of two forms.
Some chemicals act quickly and lose their therapeutic action very quickly. Vitamin C is a good example of this. You really have to take this at least five times a day.
Many betablockers have to be taken 2-3 times a day. Bisoprolol is described in BNF76 as having "an intrinsically longer duration of action".
Amiodarone is at the other extreme. The elimination half life is 15-142 days.
To simplify matters, the 'half life' is often talked about. The concept relates to the maths of exponential curves. If the half life is 16 hours, then half the drug will be lost after 16 hours, a half of a half after another 16 hours etc. The rule of thumb is that significant effect is lost after 3-5 half lives.
Now, unfortunately, the handbook popular in Britain, the British National Formulary, does not usually state half-lives. For that you need websites like rxlist.com rxlist.com/drugs/alpha_a.htm and drugs.com professional, and for once, Wikipedia is not bad.
Another complicating factor is how fast an individual metabolises a drug. This is genetic. Recent research has shown that there are 4 types of metabolisers and drug dosing is matched to only one of them. So if you personally fall into one of the other categories you could be metabolising too quickly in which case you would need a higher dose or too slowly in which case you might be getting a toxic build up. There is now genetic testing to determine which category one falls into but such an individualised dosing of meds is not likely to be rolled out any time soon. As well as this genetic difference there is also the complicaction of those who have poor metabolism due to impaired liver function.
Thanks. Helpful. There are also male/female differences, and differences due to hormone cycles, and differences due to size and weight and age. All this is usually covered in the term 'individual variation'.
The other thing that could make a difference in take up rate is the make of drug. I was told that what I would describe as `baulking` products are different say between Cardiacor and Sandoz. Only 80%? has to be Bisoprolol Fumarate by law and the remainder is down to the manufacture. This is what the manufacture is allowed to alter to make the product cheaper.
This is what annoys me when the Pharmacy tries to give you a different make and insists it is the same . It is a bit like saying all tins of tomato soup are the same!
Mgs
From what I understand the drug is made to act as a 24 hour drug hence the once a day. I was on 10 mg but reduced to 7.5 mg mainly because my PH meds made my BP drop to low. I have never been told to split it.
I believe it is also the pharmaceutical's aim to make the drug as easy to take as possible and believe taking a dose once a day less likely to be forgotten. That does not mean that according to individual variation and preference, splitting the dose might be preferred.
I feel some of the replies seem to be looking at Bisoprolol as a pill in the pocket type of medication, it is in fact a slow release drug and so it is the level of dosage not time of day that is more important, as someone in permanent AF, my 1.25 is taken first thing in the morning to control my heart rate at the same level throughout the day. hope that helps
Another Question!
Bisoprolol 
BISOPROLOL
Reducing Bisoprolol dosage
