The headache caused by not knowing which way the Food and Drug Administration will rule on MAP Pharmaceuticals' (Nasdaq: MAPP) Levadex is almost over. Monday is the agency's goal for handing down a ruling on the migraine drug.

The active ingredient in Levadex is dihydroergotamine, a drug that's been on the market since Truman was president. MAP's version is dosed via an inhaler rather than injected or used as a nasal spray like Valeant Pharmaceuticals' Migranal.

The efficacy data look good -- no big surprise there given the drug's history -- and safety doesn't seem to be much of an issue. The most common adverse event was medication aftertaste that 6% of patients experienced. Nausea was reported in 5% of patients, but that's still lower than Migranal, where 10% of patients in the trials experienced nausea.

According to MAP, the FDA thought the data from one pivotal phase 3 trial were enough. That's a little unusual -- typically two phase 3 trials are required for all but the most serious indications -- but maybe it's not all that surprising since Levadex is just a reformulation of an old drug.

The biggest unknown variable has to do with that reformulation. The FDA hasn't been particularly keen on inhaled drugs that treat issues that have nothing to do with lung function. Pfizer's (NYSE: PFE) inhaled insulin Exubera, which it licensed from Nektar Therapeutics (Nasdaq: NKTR), had a signal suggesting that it might be causing lung cancer. And the agency rejected Alexza Pharmaceuticals (Nasdaq: ALXA) inhaled antipsychotic Adusuve Staccato because of decrease in lung function after taking the drug. MannKind (Nasdaq: MNKD) has also struggled to get its inhaled insulin Afrezza approved, although lung function issues don't seem to be the problem.

On the plus side, patients don't have migraines every day, so the inhaled product wouldn't be used as often as it would for a chronic condition, which could mitigate some of the FDA's hard-line stance on inhaled products.

Taken together, I think it's more likely than not that the FDA will approve Levadex, but it's far from a sure thing. What's your take? Vote in the poll below and then fill in the details of what swayed your vote in the comment box further down.