When Your Marplan Prescription Can't Be Filled

For patients with treatment-resistant depression, Marplan (Isocarboxazid) can be a lifeline. But in 2026, finding Marplan at your pharmacy is easier said than done. Ongoing shortages, sole-source manufacturing, and no generic availability have left many patients scrambling — and sometimes going without their medication.

If you can't fill your Marplan prescription, it's important to know that there are alternatives. This guide covers what Marplan is, how it works, and the other medications your doctor might consider if Marplan isn't available.

Important: Never switch medications on your own. All of the alternatives listed here require a prescription and should only be started under the supervision of your psychiatrist or prescribing physician.

What Is Marplan and How Does It Work?

Marplan is the brand name for Isocarboxazid, a medication in the monoamine oxidase inhibitor (MAOI) class. It was FDA-approved for the treatment of major depressive disorder, particularly in patients who haven't responded to other antidepressants like SSRIs or SNRIs.

MAOIs work differently from most modern antidepressants. Instead of targeting a single neurotransmitter system, Marplan irreversibly blocks the enzymes MAO-A and MAO-B. These enzymes normally break down serotonin, norepinephrine, and dopamine in the brain. By blocking them, Marplan allows these neurotransmitters to build up, which can significantly improve mood and reduce symptoms of depression.

This broad mechanism is why MAOIs can be effective for patients who don't respond to newer, more targeted medications. However, it also means MAOIs come with strict dietary restrictions — particularly the need to avoid tyramine-containing foods — and a long list of drug interactions.

For a deeper dive into Marplan's mechanism, see our article on how Marplan works.

MAOI Alternatives to Marplan

If Marplan isn't available, your doctor may consider switching you to one of the following MAOI alternatives. All three are FDA-approved antidepressants with a similar mechanism of action.

1. Nardil (Phenelzine)

Nardil is the most commonly prescribed alternative to Marplan. Like Isocarboxazid, Phenelzine is a non-selective, irreversible MAOI in the hydrazine class. It works by the same basic mechanism — blocking MAO-A and MAO-B to increase serotonin, norepinephrine, and dopamine levels.

Key facts about Nardil:

• Available as 15 mg oral tablets
• Typical dose range: 45-90 mg per day
• Same dietary restrictions as Marplan (must avoid tyramine-containing foods)
• Similar side effect profile: orthostatic hypotension, weight gain, insomnia, sexual dysfunction
• Has also experienced supply issues, though availability may differ from Marplan at any given time

Because Nardil is in the same chemical subclass as Marplan, it may be the closest pharmacological match for patients switching from Isocarboxazid.

2. Parnate (Tranylcypromine)

Parnate is another non-selective, irreversible MAOI, but it belongs to the non-hydrazine class. It was FDA-approved for major depressive disorder and has been available since the 1960s.

Key facts about Parnate:

• Available as 10 mg oral tablets
• Typical dose range: 30-60 mg per day
• Same tyramine dietary restrictions apply
• May have a slightly more activating effect compared to Nardil — some patients find it less sedating
• Side effects include insomnia, dizziness, dry mouth, and orthostatic hypotension
• Weight gain may be less pronounced than with Nardil or Marplan

Parnate is often preferred by psychiatrists who want an MAOI with a somewhat more stimulating profile.

3. Emsam (Selegiline Transdermal Patch)

Emsam is unique among MAOIs because it's delivered through a skin patch rather than a pill. Selegiline, the active ingredient, is selective for MAO-B at low doses but inhibits both MAO-A and MAO-B at higher doses — making it effective for depression.

Key facts about Emsam:

• Available as a transdermal patch in 6 mg/24 hr, 9 mg/24 hr, and 12 mg/24 hr doses
• At the lowest dose (6 mg/24 hr), no dietary restrictions are required — a major advantage over other MAOIs
• At higher doses, the same tyramine precautions apply
• The patch bypasses first-pass metabolism in the gut, which is why the dietary restrictions are relaxed at low doses
• Common side effects include application site reactions, insomnia, and headache
• Generally more expensive than oral MAOIs

Emsam may be a good option for patients who find the dietary restrictions of traditional MAOIs particularly burdensome. However, it may not be as potent for severe, treatment-resistant depression as the oral MAOIs.

What About Non-MAOI Alternatives?

If your doctor determines that an MAOI isn't the best path forward, or if none of the MAOI alternatives are available either, there are other medication classes that may help with treatment-resistant depression:

• Tricyclic antidepressants (TCAs) like Nortriptyline or Amitriptyline
• Atypical antidepressants like Mirtazapine
• Augmentation strategies such as adding Lithium or an atypical antipsychotic to an existing antidepressant
• Ketamine-based treatments like Spravato (Esketamine nasal spray)

These are not direct substitutes for Marplan and work through different mechanisms, so the decision to try them should be made carefully with your psychiatrist.

Final Thoughts

Losing access to a medication that's managing your depression is stressful and scary. If you can't find Marplan, know that alternatives exist — and your prescriber can help you find the best option for your situation.

Before switching, try using Medfinder to locate Marplan in stock near you. If it's truly unavailable, talk to your psychiatrist about Nardil, Parnate, or Emsam as potential substitutes.

For more on the current shortage, read our Marplan shortage update for 2026.