The study described is characteristic of a Phase II clinical trial. Key indicators include the small sample size (30 subjects), the focus on a specific patient population ("subjects with chronic arthritis"), and the dual objectives of evaluating preliminary effectiveness and determining common short-term side effects. Phase II studies are the first to test a drug in patients with the target condition to assess efficacy, explore dosing, and further evaluate safety before committing to larger, more expensive Phase III trials. The nonrandomized design is also common in early exploratory studies.

A. Phase I studies primarily assess safety, tolerability, and pharmacokinetics, typically in a small number of healthy volunteers, not for effectiveness in patients.

C. Phase III trials are large-scale, pivotal studies involving hundreds to thousands of subjects, usually randomized and controlled, to confirm efficacy for regulatory approval.

D. Phase IV studies are post-marketing surveillance conducted after a drug has been approved and is on the market to monitor long-term safety and effectiveness.

1. U.S. Food and Drug Administration (FDA), Code of Federal Regulations Title 21, Part 312.21 (21 CFR § 312.21). This regulation defines the phases of a clinical investigation.

Section 312.21(b) Phase 2: "Phase 2 includes the controlled clinical studies conducted to evaluate the effectiveness of the drug for a particular indication or indications in patients with the disease or condition under study and to determine the common short-term side effects and risks associated with the drug. Phase 2 studies are typically well controlled, closely monitored, and conducted in a relatively small number of patients..."

2. National Institutes of Health (NIH), National Cancer Institute (NCI). "NCI Dictionary of Cancer Terms - Phase II trial".

"A type of clinical trial to study the safety and how well a new treatment works in a larger group of people (usually fewer than 100) who have a particular disease or condition. Phase II trials also study the best dose of the new treatment."

3. Friedman, L. M., Furberg, C. D., & DeMets, D. L. (2015). Fundamentals of Clinical Trials (5th ed.). Springer.

Chapter 3, "What Is the Question?", Section on Phase II Trials (pp. 26-27): This chapter describes Phase II trials as typically being the first evaluation in patients with the disease, focusing on treatment activity or efficacy and short-term safety, often with a sample size ranging from 20 to 200 participants.