There are a number of different beta blockers, all with the potential to worsen myasthenia probably both pre and post synaptic (see medications and myasthenia at myasthenia.org). Atenolol and metoprolol are the most innocent, propranolol reportedly the worst offender. I have not noticed any change in myasthenic symptoms related to whether I was on or off metoprolol or off antihypertensives entirely. If you have high blood pressure, and are on other drugs like Imuran, your choices may become limited. I did have marked difficulties with the calcium channel blockers, which also did not control the hypertension.

I took propranolol while on Imuran. I got so weak I could not climb stairs or get out of a chair when sitting. I started to have trouble breathing and didn't have a clue as to why so went to an allergist thinking I was allergic to something. Fortunately, he was brilliant and told me the beta blockers were the culprit. I went off of it and it took about 6 months recovery time but I was able to breathe and walk again. I take a calcium channel blocker and ace inhibitor now and do not have problems with the MG but my hypertension is not controlled as well as before. Be careful.

Ah, within the last week, I have been put on low doses of Carvedilol and Lisinopril. Taken off Metoprolol. (All heart meds.)
Does Carvedilol or Lisinopril worsen MG symptoms? (I'm checking, b.)
- Ross

From Drugs.com.

Beta-Blockers (Includes Carvedilol) Myasthenia Gravis
Moderate Potential Hazard, Low plausibility
Applies to: Myoneural Disorder
Beta-adrenergic receptor blocking agents (aka beta-blockers) may potentiate muscle weakness consistent with certain myasthenic symptoms such as diplopia, ptosis, and generalized weakness. Several beta-blockers have been associated rarely with aggravation of muscle weakness in patients with preexisting myasthenia gravis or myasthenic symptoms.

I'll be asking my Neuro.
- Ross
PS: Lisinopril is not listed as having a negative effect on MG symptoms.

Ross,
I take both metoprolol and lisinopril. I. Really have no problems other than if I take the lisinopril the day before and day of plex by blood pressure will bottom out during treatment.
Annette

Thanks for your input, Annette.
Before my recent switch from Metoprolol to Carvedilol, my Neuro also instructed me - not to take the Metoprolol - before IV-Therapy, whether it was Rituxan or IVIG.
For the same reason as you, to prevent my blood pressure from dropping too low. (I would take the Metoprolol, after IV-Therapy.)

I had IVIG today - and interestingly enough - my blood pressure was slightly lower than normal.
Well, duh. I had taken the Carvedilol before IV-Therapy.
No one had instructed me - not - to take it. Guess I better run this by the doctors, huh?
Thanks again - Ross