In a news release from mid-July, 2021, biopharmaceutical company Strongbridge Biopharma plc (“Strongbridge”) shared the publication of new post hoc analyses regarding KEVEYIS (dichlorphenamide) for patients with Primary Periodic Paralysis (PPP). Altogether, the data stems from a 1-year open-label study and showed the safety, efficacy, and tolerability of long-term KEVEYIS use. Interested in learning more? Check out the published findings in Muscle & Nerve.
So what exactly is KEVEYIS? According to Strongbridge, KEVEYIS, granted Orphan Drug designation:
is the first and only FDA-approved treatment for hyperkalemic, hypokalemic, and related variants of Primary Periodic Paralysis – an ultra-rare neuromuscular disorder. In 2 clinical studies vs. placebo, KEVEYIS was shown to reduce the number, duration, and severity of attacks of Primary Periodic Paralysis.
The treatment is given as a 50mg pill taken 1-2x daily. In the recently published data, findings included:
- KEVEYIS was safe, effective, and well-tolerated over time. Altogether, the treatment offered a sustained benefit, which researchers observed during the 61-week study period.
- Generally, the therapy was relatively well-tolerated. However, some adverse reactions did occur. These include confusion or difficulty focusing/paying attention, changes in taste, or a “pins and needles” sensation. Doctors do note that lowering the KEVEYIS dose could reduce or prevent these side effects from occurring.
- In many patients, KEVEYIS reduced “attacks” characterized by muscle weakness and paralysis. By the end of the study period, many patients were no longer experiencing weekly PPP attacks.
Primary Periodic Paralysis (PPP)
Primary Periodic Paralysis (PPP) consists of a group of rare and inherited neuromuscular disorders, such as hypokalemic periodic paralysis (HOKPP) or hyperkalemic periodic paralysis (HyperKPP). A variety of genetic mutations play a role in PPP. For example, CACNA1S, KCNJ18, and SCN4A gene mutations are all associated with HOKPP. Generally, the genetic mutations change the way that sodium, chloride, potassium, and calcium move in and out of cells and through cellular channels. As a result, skeletal muscles don’t respond to electrical impulses, causing paralytic attacks, muscle weakness, and stiffness. Additionally, external factors like illnesses, medications, or even a carbohydrate-rich diet can trigger PPP attacks.
Symptoms and onset depend on which form of PPP someone has. While some patients experience attacks in early childhood, many do not experience symptoms until late childhood or early adulthood. Others may not show symptoms until their late adulthood. While symptoms vary between forms, symptoms may include:
- Muscle cramping
- Pain following exercise
- Muscle weakness lasting minutes to days
- Permanent weakness (often later in life)
- Facial weakness
- Irregular heartbeat
- Difficulty chewing or swallowing