Why Drug Interactions Matter With Crexont XR

Crexont XR (Carbidopa/Levodopa extended-release capsules) treats Parkinson's disease by delivering Levodopa to your brain. But certain medications, supplements, and even foods can interfere with how Crexont XR works — making it less effective or causing dangerous side effects.

This guide covers the most important interactions so you can have an informed conversation with your doctor. If you're new to Crexont XR, start with our overview of Crexont XR.

Dangerous Interactions: Medications You Must Avoid

Nonselective MAO Inhibitors — Contraindicated

This is the most serious interaction. Do not take Crexont XR if you are currently taking or have recently taken (within the past 14 days) a nonselective MAO inhibitor, including:

• Isocarboxazid (Marplan)
• Phenelzine (Nardil)
• Tranylcypromine (Parnate)

Combining these medications with Crexont XR can cause a dangerous spike in blood pressure (hypertensive crisis). Your doctor must stop the MAO inhibitor at least 14 days before starting Crexont XR.

Medications That May Reduce Crexont XR's Effectiveness

Dopamine D2 Receptor Antagonists

These medications block dopamine receptors in the brain, which can work against the effects of Crexont XR:

• Phenothiazines (Chlorpromazine, Prochlorperazine)
• Butyrophenones (Haloperidol)
• Risperidone (Risperdal)
• Metoclopramide (Reglan) — commonly used for nausea

If you need an anti-nausea medication, talk to your doctor about alternatives to Metoclopramide that won't interfere with Crexont XR.

Isoniazid

Isoniazid, used to treat tuberculosis, may reduce the effectiveness of Levodopa. If you need treatment for TB, your doctor should monitor your Parkinson's symptoms closely.

Phenytoin

Phenytoin (Dilantin), a seizure medication, may reduce the effectiveness of Levodopa. Your doctor may need to adjust your doses if you take both.

Papaverine

Papaverine, sometimes used for blood vessel problems, can reduce Levodopa's effectiveness. Tell your doctor if you take this medication.

Medications That Increase Side Effect Risk

Selective MAO-B Inhibitors

Unlike nonselective MAO inhibitors (which are contraindicated), selective MAO-B inhibitors are sometimes used alongside Carbidopa/Levodopa. However, the combination increases the risk of orthostatic hypotension (dizziness when standing). These include:

• Rasagiline (Azilect)
• Selegiline (Eldepryl, Zelapar)
• Safinamide (Xadago)

Your doctor may still prescribe these together but should monitor your blood pressure carefully.

Supplements and Over-the-Counter Interactions

Iron Supplements

Iron salts (including ferrous sulfate, ferrous gluconate, and multivitamins with iron) can reduce Levodopa absorption. If you take iron supplements:

• Take them at least 2 hours before or after Crexont XR.
• Tell your doctor so they can monitor whether your Parkinson's symptoms are well controlled.

Food and Beverage Interactions

High-Protein Meals

Levodopa is an amino acid that competes with dietary protein for absorption. Eating a high-protein meal at the same time as Crexont XR can reduce how much Levodopa gets into your brain. Tips:

• Space protein-heavy foods away from your Crexont XR doses.
• You don't need to avoid protein entirely — just be mindful of timing.
• Some patients find it helpful to eat more protein at dinner if they take their last dose earlier in the day.

Alcohol

Do not drink alcohol-containing beverages when taking Crexont XR. Alcohol may increase the rate at which Levodopa is released from the extended-release beads, potentially increasing side effects like dizziness, nausea, and drowsiness.

Iron-Rich Foods

Like iron supplements, iron-rich foods (red meat, spinach, fortified cereals) can reduce Levodopa absorption if eaten at the same time as Crexont XR. Try to space these foods away from your doses.

What to Tell Your Doctor Before Starting Crexont XR

Before starting Crexont XR, make sure your doctor knows about:

1. All prescription medications you take, especially antipsychotics, anti-nausea drugs, and blood pressure medications.
2. Over-the-counter medications including antacids, iron supplements, and multivitamins.
3. Herbal supplements — some may interact with Levodopa.
4. Your diet — especially if you follow a high-protein diet.
5. Any history of glaucoma — Crexont XR is contraindicated in narrow-angle glaucoma.
6. Mental health medications — especially MAO inhibitors and antipsychotics.

What If You're Already Taking a Medication That Interacts?

Don't stop any medication on your own. If you discover a potential interaction:

• Call your doctor or pharmacist.
• Ask if the doses or timing can be adjusted.
• Ask about alternative medications that don't interact with Crexont XR.

Your pharmacist can also run an interaction check when filling your Crexont XR prescription.

The Bottom Line

Crexont XR has several important drug interactions. The most dangerous is with nonselective MAO inhibitors, which must be stopped at least 14 days before starting Crexont XR. Medications that block dopamine, iron supplements, high-protein meals, and alcohol can also interfere. Always give your doctor and pharmacist a complete list of everything you take.

For more about Crexont XR, learn about side effects, how it works, or how to save money on your prescription.