Relypsa (RLYP) is aiming to secure U.S. approval Wednesday for its first drug -- a new treatment to help patients with dangerously high levels of potassium in their blood.

A positive nod from the U.S. Food and Drug Administration will prompt Redwood City, Calif-based Relypsa to finalize the hiring of a salesforce and start selling the drug within the next two months, said company spokesperson Charlotte Arnold.

Getting an early jump on a commercial launch could be enormously important for Relypsa because a competing treatment from ZS Pharma (ZSPH) is also under FDA review with a decision expected in the middle of next year.

The Relypsa drug patiromer targets hyperkalemia, a condition in which potassium levels in the blood become abnormally high, usually due to poorly functioning kidneys or as a side effect from medicines taken by people to manage heart failure and chronic kidney disease. Elevated potassium can cause abnormal heart rhythm and in worse cases, sudden death.

Patiromer is a powder suspended in a small amount of water. When swallowed, the drug binds to excess potassium in the gut, and removes it. Across multiple clinical trials, Relypsa showed patiromer reduces potassium levels back to a normal range and maintains that range out to one year, with a well-tolerated safety profile.

Relypsa is focusing the patiromer commercial effort on the approximately 3 million U.S. patients with hyperkalemia due to chronic kidney disease and heart failure. Among these 3 million U.S. patients, there are 40,000 patients hospitalized every year due specifically to hyperkalemia. Another 900,000 hospitalizations are associated with hyperkalemia annually, Relypsa says.

Right now, these patients are generally treated with a low potassium diet, reductions in use of other drugs causing hyperkalemia or with an older potassium binder, Kayexalate, which can be effective but also causes high rates of severe constipation.

In addition to its own sales force, Relypsa signed an agreement to have Sanofi's (SNY) - Get Report kidney-disease sales reps also market patiromer. Sanofi has a lot of experience selling its phosphate binders Renvela and Renagel to kidney disease doctors and dialysis clinics.

Relypsa has not announced patiromer pricing yet but spokesperson Arnold says the company intends to keep the cost of the drug at or below the $600-per-month threshold for specialty drugs under Medicare Part D.

Some analysts forecast peak patiromer sales as high as $1 billion-plus depending on price and market penetration. The analyst at Morgan Stanley is much more bearish, believing patiromer peak sales will fall below $200 million annually because of the drug's modest efficacy, difficulties convincing doctors to change the way they treat hyperkalemia and reimbursement hurdles.

Relypsa heads into Wednesday's FDA approval decision with its stock down more than 40% for the year. Shares slid hard in August after the company announced patiromer marketing agreements with Sanofi and Fresenius Medical Care (outside the U.S.). Investors viewed both marketing deals with some disappointment because it took a near-term acquisition of Relypsa off the table.

Investors, generally, see small risk that FDA rejects patiromer Wednesday but they're also taking a cautious attitude towards the drug's commercial launch.

"We recognize that the patiromer commercial launch requires us to build the market and educate doctors" about a new way to treat hyperkalemia, said Relypsa's Arnold.

The outlook for patiromer's commercial launch will be helped if FDA approves the drug with a clean label, including approvals for both acute and chronic treatment of hyperkalemia with no significant warnings or restrictions. Relypsa also hopes FDA allows once-daily dosing of patiromer.

Relypsa's market value is significantly lower than rival ZS Pharma, in part because of speculation in September that Swiss drug maker Actelion was interested in acquiring the company. ZS Pharma's hyperkalemia drug ZS-9 is under FDA review with an approval decision date of May 26, 2016.

Adam Feuerstein writes regularly for TheStreet. In keeping with company editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback; click here to send him an email.