Drug developer Cardiome (NASDAQ:CRME) finally got a response from the Food and Drug Administration about a marketing application for its lead drug, Kynapid, but it wasn’t the response that Cardiome was looking for.

Yesterday, Cardiome announced that the FDA had issued an approvable letter for Kynapid, its arrhythmia heart treatment. Even worse for Cardiome and marketing partner Astellas, the FDA asked for more clinical-trial data on Kynapid before it will approve the drug.

Cardiome’s Kynapid marketing application has had the distinction of being subjected to one of the longest FDA review delays in recent memory; it took the FDA took nearly seven months beyond the Jan. 19 PDUFA date to make any sort of decision.

Cardiome was vague on what exactly would be needed to get Kynapid approved, and Astellas will be meeting with the FDA to find out exactly what steps the companies need to take next. But the important takeaway for investors should be this line from Cardiome’s press release yesterday: “We expect that several months may be required to assemble a complete and appropriate response.”

If it takes “several months” for Cardiome and Astellas to gather a response to the approvable letter, then there will probably be enough data in the response for them to get hit with at least a six-month class 2 FDA approvable letter review (rather than the shorter 60-day review that some approvable letter responses get from the FDA). In other words, it could be at least another nine months to a year before Kynapid makes it to the market -- and that may be a best-case scenario, depending on what the agency asks of Astellas and Cardiome.

Approvable letters are nothing new for drugmakers, but this one is particularly surprising because the drug was subjected to a positive FDA advisory panel hearing last year. That panel voted 6-2 in favor of recommending it for marketing approval. Also, the FDA submitted briefing documents in conjunction with that hearing that were mostly positive about Kynapid, albeit with questions about how broad or strict of a label to attach to the drug.

Aside from a few compounds that the FDA has outright rejected for approval -- like Vanda Pharmaceuticals(NASDAQ:VNDA) iloperidone, or drugs for terminal indications like Genentech’s (NYSE:DNA) Avastin breast-cancer filing -- the FDA’s Center for Drug Evaluation and Research (CDER) has been summarily delaying nearly all new drug marketing applications this year by anywhere from a couple of weeks to several months.

After the positive advisory-panel hearing and FDA briefing documents, I had expected a fairly quick FDA approval of Kynapid. How wrong we can sometimes be in a changing FDA regulatory environment, though! Last year, Neurocrine Biosciences (NASDAQ:NBIX) claimed to have been a victim of shifting FDA regulatory winds as well; the FDA may have raised the hurdles for approval of its insomnia drug, indiplon, without warning.

Cardiome has finally gotten an FDA response on its Kynapid marketing application. But it’s had to face a lengthy delay from the agency’s cardio-renal division, not to mention the potential raising of the hurdles the company must jump through for approval. All this surely can’t make other drugmakers awaiting marketing application responses from the FDA very comfortable.

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Fool contributor Brian Lawler does not own shares of any company mentioned in this article. The Fool has an A+ disclosure policy.