Phase 1 Clinical Trials of Small Molecules: Evolution and State of the Art.

BACKGROUND: Phase 1 studies comprise the first exposure of a promising new chemical entity in healthy volunteers or, when appropriate, in patients. To assure a solid foundation for subsequent drug development, this first step must carefully assess the safety and tolerance of a new compound and often provide some indication of potential effect, so that a safe dose or dose range can be confidently selected for the initial Phase 2 efficacy study in the target patient population. METHODS: This review was based on a literature search using both Google Scholar and PubMed, dated back to 1970, using search terms including "healthy volunteers", "Phase 1", and "normal volunteers", and also based on the authors' own experience conducting Phase 1 clinical trials. This paper reviews the history of Phase 1 studies of small molecules and their rapid evolution, focusing on the critical single and multiple dose studies, their designs, methodology, use of pharmacokinetic and pharmacodynamic modeling, application of potentially helpful biomarkers, study stopping criteria, and novel study designs. RESULTS: We advocate for determining the safe dose range of a new compound by conducting careful dose escalation in a well-staffed inpatient setting, defining the maximally tolerated dose (MTD) by reaching the minimally intolerated dose (MID). The dose immediately below the MID is then defined as the MTD. This is best accomplished by using appropriately screened patients for the target indication, as patients in many CNS indications often tolerate doses differently than healthy non-patients. Biomarkers for safety and pharmacodynamic measures can also assist in further defining a safe and potentially effective dose range for subsequent clinical trial phases. CONCLUSION: Phase 1 studies can yield critical insights into the pharmacology of a new compound in man and offer perhaps the only development period in which the dose range can be safely and thoroughly explored. Phase 1 studies often contain multiple endpoint objectives, the reconciliation of which can present a dilemma for drug developers and study investigators alike, but which can crucially determine whether a compound can survive to the next step in the drug development process.

A Randomized Phase I Study to Assess the Effect of Alcohol on the Pharmacokinetics of an Extended-release Orally Disintegrating Tablet Formulation of Amphetamine in Healthy Adults.

PURPOSE: There is a strong association between attention-deficit/hyperactivity disorder (ADHD) and alcohol abuse, yet no studies have systematically assessed the effect of alcohol on the pharmacokinetics of psychostimulants such as amphetamine (AMP) in vivo. This study evaluated the effects of alcohol on the rate and extent of absorption of Adzenys™ XR-ODT*, a new extended-release orally disintegrating AMP tablet (AMP XR-ODT) for ADHD. METHODS: A Phase I single-dose, open-label study was conducted in 32 healthy adults. Participants were split into 2 cohorts, allowing for close monitoring of safety profile and tolerability, and were randomized 1:1:1:1 to receive treatment in 1 of 4 sequences. Each treatment included the administration of a single 18.8-mg dose of AMP XR-ODT, followed by 240 mL of deionized water or 4%, 20%, or 40% ethanol. Blood samples were collected at prespecified time points. The pharmacokinetic profiles of d- and l-AMP were comparable across treatment groups. FINDINGS: There was no change in the extent of absorption for d- or l-AMP with alcohol coingestion and no dose dumping of the extended-release portion of the formulation. The 90% CIs for the geometric mean ratios (4%, 20%, and 40% ethanol versus water) for Cmax and systemic exposure (AUC0-5, AUClast, and AUC0-∞) were within 80% to 125%. Adverse events were mild to moderate and were consistent with the known adverse event profile for AMP XR-ODT or alcohol. IMPLICATIONS: Varying concentrations of alcohol (4%-40%) did not significantly alter the pharmacokinetic profile of AMP XR-ODT. These findings are relevant to clinicians who have concerns about alcohol use and/or abuse when treating ADHD.

Effect of rofecoxib on prednisolone and prednisone pharmacokinetics in healthy subjects.

Patients receiving nonsteroidal anti-inflammatory drug therapy may also require administration of corticosteroids, particularly patients with rheumatoid arthritis. To investigate the effect of rofecoxib on the single-dose pharmacokinetics of oral prednisone and intravenous prednisolone, the authors conducted a randomized, double-blind, placebo-controlled crossover study in 12 healthy subjects. Oral rofecoxib (250.0 mg/day for 14 days) failed to influence prednisone or prednisolone pharmacokinetics after intravenous prednisolone or oral prednisone administration. The geometric mean ratio (GMR) (90% confidence interval) of prednisolone AUC infinity (rofecoxib/placebo) following intravenous and oral corticosteroid was 0.97 (0.94, 1.01) and 0.99 (0.91, 1.08), respectively. Similarly, the prednisone AUC infinity GMRs (rofecoxib/placebo) after intravenous and oral corticosteroid were 1.03 (0.95, 1.11) and 1.08 (0.92, 1.28), respectively. The absence of an effect of rofecoxib on the pharmacokinetics of oral prednisone or intravenous prednisolone indicates that no adjustment in dose of this corticosteroid is necessary when administered concurrently with rofecoxib.