Posted by ed_uk2010 on January 29, 2015, at 12:39:00
Oral immediate-release nifedipine has been used by some as a treatment for acute hypertensive crisis induced by excessive tyramine consumption while taking an MAOI.
The use of oral nifedipine has fallen out of favour as a treatment for acute hypertension because there have been reports of angina, MI, stroke and hypotension. Personally, I think the patient characteristics and type of hypertension (acute vs chronic) are very important....
Large doses of rapid-release nifedipine are totally inappropriate in the setting of severe chronic hypertension. In this situation, gradual BP reduction is essential. If BP has been high over a long period, large/rapid reductions are dangerous. The body becomes accustomed to high BP and the perfusion of vital organs (heart, brain, kidneys etc) may be dangerously compromised by the sharp reductions which can occur after taking a nifedipine capsule. In contrast, controlled release nifedipine tablets are often very useful in chronic hypertension, and provide and safe and sustained BP reduction similar to amlodipine (Norvasc, Istin).
Another issue with nifedipine is related to patient age and underlying health status. Immediate release nifedipine is rarely appropriate for the elderly, who have generally been hypertensive over a prolonged period... and equally, may be more susceptible to developing hypotension. The increased heart rate associated with nifedipine in the setting of abruptly falling BP can cause angina in those with underlying coronary artery disease.
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Anyway, the treatment of acute-onset hypertension in younger people is different. If BP has only been elevated briefly, rapid reduction appears safe and desirable if the elevation is severe.
New guidelines for the treatment of acute-onset hypertension in pregnancy (and the post-partum period) *do* include oral nifedipine as a first-line option. I think these guidelines are interesting because, in many ways, most of the patients who have been treated effectively with nifedipine are similar to the majority of patients on this board who take MAOIs: they are young or middle-aged and have no underlying cardiovascular disease. Also, the hypertension being treated is severe and acute ie. not an exacerbation of chronic hypertension. An MAOI hypertensive crisis is very acute. The rise is BP is sharp and occurs in the setting of otherwise normal or near-normal BP. Nifedipine capsules are an interesting choice because of the very rapid absorption of the drug (the caps should simply be swallowed; there is no reason to chew them and hold the liquid under the tongue).
The guidelines for using nifedipine capsules (immediate release) for acute hypertension in pregnancy are shown below; I have removed the text specific to fetal monitoring. It seems to me that doctors could consider a similar algorithm for patients with acute MAOI/tyramine-associated hypertensive crisis. Due to the headache and associated anxiety, 650mg-1g of Tylenol and a short-acting benzodiazepine such as lorazepam (Ativan) 1mg could also be given.
Emergent Therapy for Acute-Onset, Severe Hypertension During Pregnancy and the Postpartum Period. American College of OB/GYN.
Management With Oral Nifedipine.
Notify physician if systolic blood pressure (BP) is greater than or equal to 160 mm Hg or if diastolic BP is greater than or equal to 110 mm Hg.
If severe BP elevations persist for 15 minutes or more, administer nifedipine (10 mg orally).
Repeat BP measurement in 20 minutes and record results.
If either BP threshold is still exceeded, administer nifedipine capsules (20 mg orally). If BP is below threshold, continue to monitor BP closely.Repeat BP measurement in 20 minutes and record results.
If either BP threshold is still exceeded, administer nifedipine capsule (20 mg orally). If BP is below threshold, continue to monitor BP closely.
Repeat BP measurement in 20 minutes and record results.If either BP threshold is still exceeded, administer.... (alternative treatment).
Once the aforementioned BP thresholds are achieved, repeat BP measurement every 10 minutes for 1 hour, then every 15 minutes for 1 hour, then every 30 minutes for 1 hour, and then every hour for 4 hours.
Capsules should be administered orally and not punctured or otherwise administered sublingually.
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Unfortunately, only case reports exist to support the various strategies in acute hypertension specific to MAOIs. If nifedipine or other drugs are prescribed by a psychiatrist, medical help should still be obtained by the patient. Obviously, a home BP monitor is essential if the first dose of nifedipine is going to be taken before going to hospital.
http://www.ncbi.nlm.nih.gov/pubmed/3584082
....case reports specific to MAOIs are old! It's reassuring to know that recent experience has supported the use of oral nifedipine in other types of acute hypertension, however.
poster:ed_uk2010
thread:1075710
URL: http://www.dr-bob.org/babble/20150129/msgs/1075710.html