What causes htn medications to lose its effectiveness over time? the 50mg metoprolol i started 3 months ago is now effective for only about 11 hours out of 24 hours. my systolic and diastolic after that time go into stage 1. this is disturbing?

If you take metoprolol succinate (Toprol as the brand name), it should work for 24 hours and if blood pressure is up after 12 hours you need a higher dose 75 mg or 100 mg/day if heart rate is not too low. However, if you take metoprolol tartrate (Lopressor as the brand name), it should be taken in twice a day. Naturally, it is not uncommon that a medication loses the effect overtime.

I'm not a fan as using a beta blocker as first line treatment of hypertension unless you tend to have a hyperdynamic sympathetic nervous system with a rather rapid resting heart rate or unless you have known coronary artery disease or history of ischemic stroke. Many clinicians do not recommend beta blockers as first line treatment of hypertension in adults.