Niaspan ER is extended-release** nicotinic acid. There are alternative preparations, but the only other one that is extended-release is combined with another medication called lovastatin. Niacor and Nicolar are immediate-release nicotinic acid, and Slo-Niacin is sustained release. The cost is often determined by which preparation your medical insurance company has agreed to cover. You may want to check with your doctor to see if you absolutely need the extended-release form, and if not you can consult your pharmacist or call your insurance company to see if one of these other preparations is “formulary,” i.e. your insurance covers it at less cost to you. **Extended release tablets release a consistent amount of the drug over time, compared to sustained release tablets that release the drug slowly, but not necessarily at a consistent rate.