It seems there might be a misunderstanding. Darvocet did not typically come in a formulation with 500mg of any single active ingredient.

Darvocet was a brand name for a combination medication containing propoxyphene (a mild opioid) and acetaminophen (also known as paracetamol), usually in varying strengths. The first number in the dosage often referred to the amount of propoxyphene, while the second number indicated the amount of acetaminophen.

For instance:

• Darvocet-N 100 contained 100 mg of propoxyphene napsylate and 650 mg of acetaminophen.
• Darvocet-N 50/500 contained 50 mg of propoxyphene hydrochloride and 500 mg of acetaminophen.

However, Darvocet was withdrawn from the market due to concerns about its cardiac safety and is no longer available for use. If you are in need of pain relief, it’s best to consult with a healthcare professional for alternative medications or treatments.