00:01
I'm Dr. Shukle. Let's talk about monoamine oxidase inhibitors today.
00:06
The monoamine oxidase inhibitors are drugs
that inhibit the breakdown of norepinephrine and serotonin in the presynaptic neuron.
00:17
This allows more of these neurotransmitters in to the synaptic cleft.
00:21
The increase amounts of norepinephrine and serotonin are stored in the vesicles
and then they're eventually released when the nerve fires.
00:30
We have several types of monoamine oxidase inhibitors.
00:34
They can be nonselective or selective.
00:37
The nonselective agents are seen here, there's many of them,
there's over 20 MAO-A, MAO-B inhibitors.
00:46
We also have selective agents.
00:49
The monoamine oxidase A inhibitors like maclobemide
are some of the earliest antidepressants that we've ever used.
00:58
This particular drug was sold commercially as Mannerix.
01:02
Selective monoamine oxidase type B inhibitors include drugs like selegiline.
01:08
These are also commonly used, we see them still being used today.
01:13
Side effects to these medications
are usually due to increase amounts of norepinephrine in the nerve terminals themselves,
so this can include peripheral autonomic sympathomimetic effects.
01:25
This can lower your blood pressure
and it can also increase your risk of seizures by lowering the seizure threshold.
01:36
Finally, we need to discuss the risks of serotonin syndrome inherent to these medications.
01:40
This process is usually occurs on a patient's switches from an SSRI to MAOI.
01:45
If the initial medication is not given adequate time to be eliminated from the body,
before starting the new drug, there can be a synergistic effect on serotonin levels.
01:54
Symptoms of high serotonin can include confusion, fevers,
vomiting, sweating, and in some cases even seizures.
02:02
This condition can be life threatening so care must be taken
to ensure that this medications aren't accidentally combined
by a patient or doctor unknowingly,
and ensure that patients follow a strict taper schedule when switching their medications.
02:13
Now, what's up with the blood pressure?
I just finished saying that there was more norepinephrine in the synaptic cleft.
02:22
If it's sympathomimetic, it should cause more blood pressure and higher blood pressure.
02:26
Well, in the absence of an indirect sympathomimetic,
monoamine oxidase inhibitors actually cause a drop in blood pressure,
that's a little bit hard to remember.
02:39
In the presence of an indirect sympathomimetic,
monoamine oxidase inhibitors cause a rise in blood pressure.
02:47
Monoamine oxidase inhibitors, I'll say MAOIs from now on,
may cause severe hypertension in patients taking things like tyramine.
02:56
Tyramine is metabolized by monoamine oxidase.
03:00
Tyramine is found in things like aged-cheeses, soybeans,
beers, and red wine, cured and processed meats.
03:11
So, when you're talking about a wonderful Charcuterie board like this,
you're talking about a tyramine overload.
03:19
If you have this kind of a picnic, or a romantic dinner
and you're on a monoamine oxidase inhibitor,
you can run into the risk of having very high blood pressures in the presence of those drugs.