What has prompted the addition of another antihypertensive drug to your regimen after more than two years of good blood pressure control? Has your blood pressure started to rise?
Finding another person on the same drug combination as yours that visits these boards might be difficult. Clonidine, as an antihypertensive agent, is not used as frequently as the others. Clonidine is one of few drugs with low molecular weight, and, as such, crossess the blood-brain barrier. The result is a reduced sympathetic outflow from CNS, decreased peripheral resistance, renal vascular resistance, heart rate and blood pressure. Some people have tolerance for its antihypertensive effect, so it may not always reduce the blood pressure.
In general, the likelihood and severity of adverse reactions to any multidrug therapy increases with the number of drugs taken. In most clinical trials the participants take no more than two or three drugs. So, a combination of several drugs has likely never been tested for safety or effectiveness. This means that the exact adverse reactions to a given drug combination in the short and long-term use cannot be anticipated. There are many factors that effect our response to drugs - salt sensitivity, plasma renin activity, SNS activity, co-existing diseases, age, race, physical characteristics, metabolism, activity level and lifestyle to name a few.
One thing to watch for with Clonidine is a sudden increase in blood pressure if you miss a couple of doses or stop taking it abruptly. It should be discontinued only under your doctor's supervision. Another thing to keep an eye on are the potential additive effects -such as bradycardia or an AV block-when used with other drugs that effect the sinus node function or the AV conduction, such as beta blockers (which you take), calcium channel blockers and digitalis. In addition to the ones mentioned, cardio, CNS and other adverse effects are also possible. Do your research. I am sure your doctor will monitor your progress and any adverse effects. Good luck with your blood pressure control.