|MadSci Network: Medicine|
Hello Eric! Thank you for your question. You asked: "Why would Rogaine give chest pains? It's listed as one of the rare side effects... I'm curious as to why in the world a topical solution would give someone chest pains? What are the interactions of the chemicals which cause sensations of pain in a different part of the body? Is it serious or damaging?" ***The following information is not presented as medical advice by MadSci or G. Monreal and should not be taken as such. All the information summarized and explained below can be found in further detail on the following excellent websites: www.regroe.com/works.html www.rxmed.com/monographs2/minoxi.html Rogaine contains the ingredient minoxidil, which is a vasodilator. A vasodilator works to lower blood pressures by relaxing the peripheral vessels and increasing perfusion of the tissues. This relaxation decreases the resistance inside the vessels and creates an overall decrease in systemic blood pressures. If the pressures drop too much, the body will compensate by increasing the heart rate in an effort to maintain appropriate circulation, and the body may also retain fluids in an effort to add more volume to the circulation (which increases pressures). Vasodilator --> Relaxation of the peripheral blood vessels --> Decrease in systemic blood pressure -------- if pressures drop too much, then: Low pressures --> Increased Heart Rate and Retention of Fluids --> Blood pressures come back up Vasodilators are used to help lower blood pressures in people who have high blood pressures (hypertension) by reducing the afterload on the heart, so the heart doesn't have to work as hard to pump the blood through the body. OK, how do they help? Here's an analogy: Imagine taking a mouthful of water and trying to blow that set volume through a coffee stirrer in a fixed amount of time. The coffee stirrer is very, very narrow (has high resistance), and you will have to work very hard to blow all the water through in enough time. The pressures inside that straw as the water pushes through will be very great, and you will be tired afterwards (you are the heart). This situation is comparable to someone with high blood pressures. Now, imagine that you have to blow the same amount of water in the same amount of time through a regular drinking straw. The straw is wider (like a dilated vessel), and the resistance inside is lower, so you will not have to work so hard to push that water through, nor will you be as tired afterwards (you, as the heart, will appreciate not being as tired!). Now, what does all this have to do with minoxidil?? Back in the early 1980's, minoxidil came onto the market as a drug for lowering high blood pressures. Scientists and doctors theorized that since it is a vasodilator, it should dilate the blood vessels in the scalp, perfusing the scalp tissue with oxygen-rich blood and nutrients in hopes of stimulating the growth of new hair follicles and encouraging cell division of the hair matrix cells, producing thicker strands. So why is one of the extremely rare side effects of minoxidil chest pains? If someone is already taking antihypertensive medication for high blood pressure and decides to use minoxidil, in theory the addition of this second pressure-lowering agent could drop the blood pressures lower than they need to be. Likewise, someone in congestive heart failure may already have low pressures to begin with. Their heart is already beating faster, and the body is already retaining fluids in an effort to maintain pressures. Adding a vasodilator to that mix could, in theory, make the situation worse by lowering pressures even further (and thus encouraging the heart to beat even faster and the body to retain even more fluids). How do chest pains develop from all this? When pressures get too low for whatever reason, and the heart is unable to perfuse it's own coronary vessels adequately, regions of the heart can become ischemic as the oxygen supply to that area is reduced. The heart then switches from aerobic to anaerobic respiration, and toxic by-products accumulate (such as lactic acid), leading to fatigued heart muscles and chest pains. Hope this information helps to answer your questions! Sincerely, G. Monreal
Try the links in the MadSci Library for more information on Medicine.