Hi RLR, everyone,

I was hoping you might be able to talk briefly on this topic. I took Hyoscine Hydrobromide for the first time yesterday for travel sickness (brand name Kwells), which has recently started to bother me sometimes in the car. After reading the instructions I thought I would be safe to take it and I noted the label said use with caution in patients with heart disease. I obviously don't have heart disease so wasn't too bothered by that part, but around 40 minutes after taking this drug I realised my heart was beating much slower than normal, probably around 60-65 BPM, approximately 30BPM slower than 'normal' for me. With this also came slight dizziness, lightheadedness and drowsiness. The leaflet said that these are normal side effects, so I'm assuming they were because of lowered blood pressure from the slower heart rate but I'm unsure of this and I'm too paranoid to check my BP. I've no reason to take the tablet again unless I'm going to be travelling for more than 30 minutes, but I wanted to ask you some questions.

1. The reduction in heart rate seemed to be quite significant. Is this because the drug has anti-anxiety effects, or it physically slows the heart by a known mechanism?

2. Regardless of what mechanism slows the heart, can this drug be taken for long term relief of the 'fast heart' syndrome that I seem to have been experiencing for the last couple of years?

3. Is the dizziness and lightheadedness because blood pressure is lowered by the reduction in heart rate?

I don't check my BP anymore but a few months ago in hospital my BP was as low as 76/40 (I was in with suspected pelvic sepsis), though it has since gone back to normal (I don't know what normal is for me though). The guy in the bed next to me (who had BP readings of over 230/120) took delight in telling me "low is as bad as high" and I don't want to go around feeling dizzy all day. This is contradictory to what I've heard about getting it "as low as possible without sympoms". I also read online that if it goes much below 70 (systolic) then your kidneys and liver begin to fail.

Thanks for reading.

Okay, Hycoscine Hydrobromide, commonly called Scopalamine, acts upon cholinergic fibers associated with smooth muscle and cardiac tissues and is responsible for producing the CNS depressant effect, hence acting to reduce smooth muscle of the GI tract and also inhibits signals to the reticular formation and vomit center in the brain.

Because of these mechanisms of action, it is commonly used as an antiemetic to treat motion sickness. This is not the drug to be used off-label for purposes of lowering the heart rate. The drug acts upon cholinergic fibers and therefore typically produces an anticholinergic effect, ie dry mouth, constipation, blurred vision, decreased sweating, urinary retention and a host of other bothersome side-effects. In other words, the drug blocks or impedes parasympathetic nervous action.

While the drug increases vagal activity, which lowers heart rate, it is not designed to be used on a regular basis by any means.  Blood pressure is reduced by the drugs action on baroreflex sensitivity.

I'm also constrained to point out that contemplating advice from "the guy in the bed next to yours" would be reckless. Suffering from a disease does not qualify one to evaluate it from a clinical standpoint, much less provide sage advice.

The lightheadedness is a side-effect of the drug as much as it is the mild hypotensive effects caused by the drug's action on the vascular system.

Best regards and Good Health