Hi Parkiwife, First Thank your husband for participating in this clinical trial. If Duodopa becomes licensed in the US, it will be in large part due to his efforts.
Usually, Phase 1 studies involve a very small number of individuals. Phase 1 studies are to show safety of the drug (though this drug formulation has been used in Europe for many years now and why those trial data cannot be utilized by the US, I have no insight.) The explanation of the phases of drug study are below--note the phase 4 which the FDA usually recommends after okaying a drug and is never ever done as far as i can discern.

" Clinical trials involving new drugs are commonly classified into four phases. Each phase of the drug approval process is treated as a separate clinical trial. The drug-development process will normally proceed through all four phases over many years. If the drug successfully passes through Phases 0, 1, 2, and 3, it will usually be approved by the national regulatory authority for use in the general population.
Phase 0: Pharmacodynamics and Pharmacokinetics
Phase 1: Screening for safety
Phase 2: Establishing the efficacy of the drug, usually against a placebo
Phase 3: Final confirmation of safety and efficacy
Phase 4: Sentry studies during sales"
http://en.wikipedia.org/wiki/Clinical_trial