For any development stage-drugmaker, moving drug candidates promptly and efficiently through clinical testing should always be priority No. 1. This week, Alexza Pharmaceuticals (Nasdaq: ALXA) showed that it's delivering on at least part of this goal.

Today, Alexza announced that it had completed enrollment of a phase 2 proof-of-concept study for its inhaled panic-disorder drug, Staccato alprazolam. Yesterday, Alexza also announced the first phase 1 results for another compound in its growing drug pipeline.

This phase 1 compound, Staccato zaleplon, is a formulation of King Pharmaceuticals' (NYSE: KG) soon-to-be-generic Sonata insomnia treatment. King's sales of Sonata totalled $79 million last year, down from the $86 million it brought in during 2006; generic competition against Sonata is expected to ramp up this quarter.

The phase 1 clinical trial for Staccato zaleplon was only a short-term safety study in healthy people; it suggests nothing about the drug's potential long-term safety issues. Ironically, one of the study's most common adverse events was somnolence, better known as drowsiness. Perhaps that bodes well for the drug's ability to treat insomnia?

While Staccato zalepon's short-term safety profile sounds mild, any drug administered via the lungs often stirs regulators' (and analysts') concerns about long-term potential pulmonary safety issues. Though comparisons between Alexza's offerings and inhaled insulin compounds from MannKind (Nasdaq: MNKD) and others are tenuous at best, it's not unreasonable to think that the FDA will take a hard stance here. The agency may require Alexza to run all sorts of long-term safety tests before approving any of its compounds for these often-chronic conditions.

Alexza currently has five drugs in its pipeline that have completed phase 1 testing. Its lead drug is an inhaled version of schizophrenia treatment loxapine; it's in phase 3 testing now, with results expected in about a year. Alexza is using formulations of previously proven generic or soon-to-be generic drugs, so efficacy shouldn't be an issue. Investors should worry more about the safety hoops Alexza must jump through to win their approval, and whether public and private insurers will pay for them if they do get approved.