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Dr. Bob is Robert Hsiung, MD,
bob@dr-bob.orgShown: posts 1 to 7 of 7. This is the beginning of the thread.
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.
Posted by SLS on January 29, 2015, at 12:55:22
In reply to Treatment of MAOI hypertensive crisis, posted by ed_uk2010 on January 29, 2015, at 12:39:00
It's too bad that oral phentolamine (Regetine) is no longer available. Upon getting to the hospital, the IV administration of phentolamine 5 mg is usually indicated. If nifedipine has already been taken, I'm not sure phentolamine is an option.
- Scott
Posted by ed_uk2010 on January 29, 2015, at 13:19:18
In reply to Re: Treatment of MAOI hypertensive crisis, posted by SLS on January 29, 2015, at 12:55:22
>If nifedipine has already been taken, I'm not sure phentolamine is an option.
Even if phenolamine was available, it probably wouldn't be available in time....
Alpha blockers (doxazosin etc) and calcium channel blockers are often used together in chronic hypertension. There doesn't seem to be any specific interaction. Phentolamine, a non-selective alpha blocker, didn't have much place in most forms of acute hypertension because it caused too much tachycardia. Unlike phentolamine, alpha-1 selective antihypertensives such as prazosin and doxazosin don't normally cause tachycardia.
Considering the amount of prazosin you take, I wonder whether it would take more than the usual amount of tyramine to induce hypertension? I'm not suggesting you perform an experiment!
Posted by ed_uk2010 on January 29, 2015, at 13:21:28
In reply to Re: Treatment of MAOI hypertensive crisis, posted by ed_uk2010 on January 29, 2015, at 13:19:18
>Even if phenolamine was available, it probably wouldn't be available in time....
I think I misunderstood you. Phentolamine isn't available here at all, in any form. The injection was discontinued years ago. Even when it was marketed here, I think it's highly unlikely that most emergency departments would stock it.
Posted by SLS on January 30, 2015, at 7:22:01
In reply to Re: Treatment of MAOI hypertensive crisis, posted by ed_uk2010 on January 29, 2015, at 13:21:28
> >Even if phenolamine was available, it probably wouldn't be available in time....
>
> I think I misunderstood you. Phentolamine isn't available here at all, in any form. The injection was discontinued years ago. Even when it was marketed here, I think it's highly unlikely that most emergency departments would stock it.
>Believe it or not, oral phentolamine was being investigated to treat erectile dysfunction about 15 years ago. I was hoping it would be approved so as to give me the option of carrying it around with me instead of nifedipine for MAOI hypertension. It proved ineffective for ED. For reasons that I don't understand, I read that phentolamine administered as Regetine i.v. is recommended unless a CCB has already been taken. Even chlorpromazine is used in emergencies.
The authors of the following article prefer giving nifedipine.
- Scott
---------------------------------------------"Advise patients taking MAOIs to purchase a blood pressure cuff or finger sphygmomanometer and learn how to take their own blood pressure. If they experience a normal headache and their systolic blood pressure is not elevated by at least 30 mm Hg, they are not having a cheese reaction and do not need to worry. MAOI headaches are typically unmistakable (they feel as if ones head is splitting apart), and blood pressure is markedly elevated.
We give patients starting on MAOIs 10-mg tablets of nifedipine and advise them that if symptoms suggesting a hypertensive crisis appear, they should bite into one tablet to release the fluid inside and then swallow it. We tell patients to repeat this in 15 minutes if the headache is not receding; if the headache persists, they should visit the emergency ward or the internists office for observation.
Although there has been concern about the risk of MI or stroke with the hypotensive effect of nifedipine, we believe it is still the best option for acute severe hypertension in patients who do not have chronic hypertension. Chlorpromazine tablets (50 mg) also will stop the headache and lower blood pressure but will leave the patient groggy for about 24 hours, with possible extrapyramidal symptoms.
In the rare instance that a hypertensive crisis occurs, the official labeling recommendation is to give IV phentolamine, but we find emergency rooms either no longer stock the drug or do not remember to do this. Send any patient who is hurting and panicky to an ER, and call to suggest what the attending might do (i.e., IV phentolamine or oral nifedipine or chlorpromazine, or the emergency physicians preference for hypertensive crisis)."
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Posted by ed_uk2010 on January 30, 2015, at 8:11:47
In reply to Re: Treatment of MAOI hypertensive crisis » ed_uk2010, posted by SLS on January 30, 2015, at 7:22:01
>I was hoping it would be approved so as to give me the option of carrying it around with me instead of nifedipine for MAOI hypertension.
Perhaps - but I'm unsure how helpful it would be to take phentolamine on top of prazosin. If you were to develop a severe hypertensive episode in spite of being on an alpha blocker already, nifedipine might in fact be more logical. Oral nifedipine is very rapidly absorbed from the capsules when swallowed whole. There is no need to chew, puncture or attempt S/L administration of the caps.
>It proved ineffective for ED.
I believe alpha blockers are effective when injected directly into the corpus cavernosum, but not systemically.
>Even chlorpromazine is used in emergencies.I've never felt convinced that chlorpromazine is a logical choice. It's thought that chlorpromazine exerts a hypotensive effect by acting as an alpha-1 antagonist, rather like prazosin. I think a selective alpha-1 antagonist would cause fewer adverse effects. Dopamine antagonists might reduce the nausea and headache however...
Posted by SLS on January 30, 2015, at 14:25:03
In reply to Re: Treatment of MAOI hypertensive crisis » SLS, posted by ed_uk2010 on January 30, 2015, at 8:11:47
> > I was hoping it would be approved so as to give me the option of carrying it around with me instead of nifedipine for MAOI hypertension.
> Perhaps - but I'm unsure how helpful it would be to take phentolamine on top of prazosin.You are right. I was thinking generally for other people.
> If you were to develop a severe hypertensive episode in spite of being on an alpha blocker already, nifedipine might in fact be more logical.
I agree with you, Ed. I usually do, even when I become disagreeable.
> Oral nifedipine is very rapidly absorbed from the capsules when swallowed whole. There is no need to chew, puncture or attempt S/L administration of the caps.
Good to know.
> >Even chlorpromazine is used in emergencies.
>
> I've never felt convinced that chlorpromazine is a logical choice. It's thought that chlorpromazine exerts a hypotensive effect by acting as an alpha-1 antagonist,I think it is considered as a possibility because it is usually readily available and comes as i.v.
- Scott
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