Peter A. LeWitt, MD, considers the mechanism of action and use of levodopa inhalation powder in patients with Parkinson disease.
Peter A. LeWitt, MD: One option for rapid treatment of OFF time would be to use levodopa in a micropowder form which can be inhaled through the lungs. The alveoli can take up the powdered form of levodopa and put it into the bloodstream more rapidly than the same drug is absorbed orally in tablet form. The advantage here is the efficiency in terms of timing and the likelihood that that inhaled dose will reach a typical bloodstream concentration that is used on top of what was left over from that last levodopa tablet in order to boost the total blood level of levodopa to a therapeutic range. And this can be used by a patient on demand when observing an OFF time starting to happen, and the patient can use it to get back ON in a reliable manner. This can be used up to several times per day.
Inhaled levodopa that is absorbed through the pulmonary route has the advantage of being the same medication, levodopa, that most patients with Parkinson disease taking orally. This is a way to augment a treatment already on board in their daily regimen. Its advantage, of course, is the rapidity and the reliability of action, but it comes with some possible adverse effects. Some patients, for example, inhaling this micropowder have some irritation of the throat and coughing as a result, and patients must learn how to use this effectively.
It also requires some assembly. Two capsules must be inserted in the inhalation device in order for a patient to be able to get the full dose needed to augment their oral medication, and to some patients, this time involved might not be desirable. It is a device that was designed with patients with Parkinson disease in mind, so it has been quite user friendly, in my experience. But the dose given is such that it may not be enough for every OFF episode, especially if a patient has waited more than 45 minutes after starting to experience OFF states. It’s an on-demand therapy for patients who are starting to wear OFF. This is how it was studied, and in my experience, that’s the best way to use it.
Transcript edited for clarity.