After much debating and hand wringing I decided today was the day I would give the new medication a go.
So what is Midodrine?
Midodrine is a drug that can be used to treat people with disorders of the autonomic nervous system which include low blood pressure, neuro-cardiogenic syncope (fainting) and postural tachycardia syndrome. It is used only after other measures have been ineffective in controlling symptoms (eg high fluid intake, additional salt in some patients, counter manoeuvres, small frequent meals, gentle exercise, compression tights etc as appropriate). It is a vasopressor/antihypotensive agent.
Midodrine hydrochloride is the generic (chemical) name but some manufacturers use their own brand names for the same drug which include Gutron, ProAmatine and Orvaten. It comes in 2.5, 5 and 10mg tablets.
How does midodrine work?
Midodrine is an α1 adrenergic agonist drug, meaning that it stimulates receptors that noradrenaline normally works on. After swallowing, it is quickly converted into another chemical that causes blood vessels to narrow, thereby increasing blood pressure. Indirectly, it can also reduce heart rate.
It reaches peak concentration in the blood about an hour after swallowing a tablet, but the effect is brief, with levels falling to half about 2-3 hours later.
The brain has a protective mechanism that stops some drugs from entering and very little midodrine crosses this blood-brain barrier. It is removed from the body by the kidneys.
How do I take midodrine?
As its effect is short lived, midodrine needs to be taken frequently throughout the day. It works best if the first dose is taken an hour or so before getting out of bed, then at 3 to 4 hourly intervals throughout the day, the last dose being taken at least 4 hours before going to bed. If necessary, the amount may be gradually increased to a maximum total dose of 30mg per day.
For me personally I am taking 2.5mg once a day at the moment, next week it will be upped to 2.5mgs twice a day as long as I have no nasty side effects!!
What are the risks of taking midodrine?
The main risk of taking midodrine is ‘supine hypertension’. This is excessively high blood pressure on lying down. One advantage of midodrine is that it only works for a short time. Not taking it within 4 hours of going to bed reduces the risk of supine hypertension.
Symptoms of supine hypertension may include palpitations (awareness of the heart beat), pounding in the ears, unexpected headache or blurred vision, although it can occur with no symptoms. If you develop these symptoms, you should stop midodrine and inform the prescribing doctor. In addition, midodrine should not be continued if it causes high or unstable daytime blood pressure.
Who should not take midodrine?
Midodrine should not be prescribed in patients with the following conditions: severe heart disease, hypertension, peripheral vascular disease (narrowing of the arteries in the legs), enlarged prostate gland causing difficulty passing urine, urinary retention (when the bladder can’t empty properly), phaeochromocytoma (adrenaline producing tumour), overactive thyroid, narrow-angle glaucoma, allergy to any component of the product. It should be used with caution in kidney disease, diabetes and cor pulmonale (large right ventricle due to severe lung disease).
What are the side effects of midodrine?
Common – tingling and itching of skin-especially scalp. This may improve with time. Goose bumps. Feeling cold
Less common – supine hypertension, urinary retention (inability to pass urine), slow or fast heart rate, palpitations, irregular heart rhythm.
Rare –nausea, indigestion, headache, agitation
Interactions with other medicines
Midodrine should be used with caution in combination with the following drugs:
Digoxin, beta blockers (eg bisoprolol, atenolol, propranolol), steroids (prednisolone, fludrocortisone), alpha adrenergic receptors stimulators (phenylephrine, methoxamine), tricyclic antidepressants, antihistamines, thyroid hormones, MAO inhibitors, dihydroergotamine) rauwolfia alkaloid medicines (reserpine), atropine, some decongestants (including over the counter preparations) and appetite suppressants. Midodrine should not be given to people taking alpha blockers (phentolamine, prazosin).
What does ‘unlicensed’ mean?
Midodrine does not have marketing authorisation in the UK for the treatment of postural hypotension or for any other indication, therefore it is an unlicensed medicine in the UK. In the USA, midodrine is licensed by the Food and Drug Administration (FDA) for the treatment of symptomatic postural hypotension. It is also licensed for use in several EU countries. An application for licensing has been submitted in the UK.
How do I obtain midodrine?
As midodrine is unlicensed in the UK, it can only be prescribed by a doctor with experience in using this drug. This is usually a hospital consultant and the midodrine is dispensed by the hospital pharmacy. Sometimes hospital consultants will issue an FP10, which is a green prescription that can be dispensed by your local community pharmacy.
GPs are often advised by their pharmacists to decline to prescribe midodrine unless they are experienced in its use. However, if the consultant provides a ‘Shared Care Agreement’ (a document which provides advice to the GP about how to prescribe, side effects, monitoring and how to contact the hospital team if there are problems), then the GP may be willing to issue a prescription.
Now I am desperately hoping this miracle drug along with the Ivabradine helps my PoTs symptoms considerably, because in the last ten months I haven’t seen enough of an improvement with just the Ivabradine. So after just one dose and with a tingly scalp I know something is working, lets just hope this is the start of finding the pieces of the jigsaw that we have been looking for.