Meridia 15 typically refers to the 15 mg dose of Meridia (generic name sibutramine), an appetite suppressant used for weight loss. 
Key Drug Information
Status: Withdrawn from the market in the United States and many other countries (including Canada and the EU) since October 2010.
Reason for Withdrawal: An increased risk of serious cardiovascular events, such as non-fatal heart attack and stroke, which outweighed the benefits of modest weight loss.
Medical Use: It was formerly prescribed as an adjunct to diet and exercise for obese or overweight patients with additional risk factors.
Dosage: The 15 mg dose was the maximum daily dose, often titrated up from an initial 10 mg dose if weight loss was insufficient.
Appearance: The 15 mg capsule is typically yellow and white.
Common Side Effects: Included increased blood pressure, rapid heart rate, insomnia, dry mouth, and constipation.