I have been a registered pharmacist for 34 years. Most drugstores and insurance companies allow you to get up to a 90-day supply of prescription medications at a time. The “Refill-Too-Soon” edit, which is what prevents you from getting a prescription right after getting another one for the same drug filled is usually set at 75% of the days supply.
For example, if you are taking a high blood pressure medication once a day, then a 90-day supply is 90 pills. Seventy-five percent of ninety days is sixty-eight days. Therefore, if we use April 1, 2010 as the day you first fill your prescription for a 90-day supply and allowing 68 days to get a refill we come up with the following schedule:
This refill schedule will result in you getting a 540 day supply in only 338 days. Keep in mind that if your physician only allows for 3 refills, you would need to get a new prescription before your fourth refill.
However, many people can not afford to pay their co-pay for a three month supply at a time, even though the cost of the medicine is less for one ninety-day supply than it is for three fills of thirty day supplies. This strategy will still work for a 30 day supply. Your 23 day (seventy-five percent) refill schedule would be as follows:
This schedule will allow you to get 480 days worth of medicine in just 345 days. The same caveat about refills applies. If your doctor only writes for 11 refills, then you will need to get a new prescription before your 12th refill.