can a beta blocker lose its effectiveness?

[Katie]

I have been on 37.5 mg. of coreg and 12.5 mg. of metoprolol  2 times daily for about 1.5 years, this was to keep my heart rate down and for arrythmias. Lately my heart rate has been up again resting about 70 to 90 , and I have noticed more arrythmias. At first the medication kept my heart rate and arrythmias more regulated now I'm not so sure. My doctor can't seem to find anything wrong. My question is can a beta blocker lose its effectiveness? Would it be worth trying something else. Also I have gained quite a bit of weight, can that have something to do with it? I have cardiomyopathy with 30- 35% function in the left ventricle?

[Cleveland Clinic, MD]

Dear Katie,
It is sometimes necessary to adjust the dosage of beta-blockers.  You are on moderate size doses so there is room to increase.  It is a bit unusual to be on two different beta-blockers so you may ask your doctor if you could take a higher dose of just one. Weight gain can be a side effect of beta-blockers but can usually be countered with diet and exercise.

[Cheryl Thorne]

How do you get the dosage of beta blockers up?  My husband has not been able to tolerate more that 6.25mg twice a day; and he doesn't tolerate that very well.  He gets extremely drowsy for a couple of hours after taking the meds.  Is it helping at this low dose?  He also has a bad aortic valve, and the dr. said he may have to stay on the low dose because of it.  He was diagnosed with CHF in 2/2000.  They found the bad valve then.  He will have surgery soon.

[yellowrose]

ive been on beta-blockers sinces i was 23 years old am taking the same dose i was taking than 5mg twice a day and dont have the  problems . i do have days where my heart skips and extra beats but no drug is going to take it compleaty away ive been told. for the most part i do good, have had weeks  where it extra beats a lot but that just seams to be a part of the pvc-pac hang in there ,

[autumn]

I am experiencing the same problem with Atenolol. I am on 100mg per day. When I first began taking it my pulse went from 120 resting down to the 60s. Also, the skipping of my heartbeat mostly stopped. Unfortunatly in the past month my pulse is right back up there along with the skipping and my doctor is concerned because my blood pressure is high once again. What's going on with these beta-blockers? She is considering switching my med.