PLYMOUTH, Minn. — Thrifty White Pharmacy has introduced the Rx Timer Cap to improve medication adherence.

The patented smart cap with a built-in LCD timer fits standard prescription vials. The cap works like a stopwatch, counting up the hours and minutes since a vial was last opened to tell patients how long it has been since their last dose.

The chain is giving away Rx Timer Caps to customers enrolled in its Ready Refill and Medication Synchronization programs. The programs ensure that maintenance medication prescriptions are refilled ahead of schedule. The caps may also be purchased.

“The No. 1 problem in treating illness today is patient failure to take prescription medication correctly, regardless of age,” says Thrifty White pharmacist Tanya Schmidt, who oversees the chain’s central fill operation. “Our stores receive several calls a day asking, ‘What should I do if I forgot to take my ­medication?’ ”

Studies have shown that less than half of all Americans take medications as prescribed by their physicians. There are many factors than can contribute to poor medication adherence, but a 2005 Harris poll found the most common was forgetfulness, which is especially common with medications for asymptomatic conditions.

Many people forget when or if they took their medication. By automatically keeping track of the interval between doses, the cap increases adherence. In an independent study conducted with the cholesterol-lowering drug Niaspan, 10,000 patients were split into two groups. The test group was given medication in containers with the Rx Timer Cap, and the control group received medication in containers with a standard cap. Over a 90-day period the test group of patients showed a 33.9% increase in compliance.

“By providing patients with this simple yet critical bit of information about when they last took their medication, the Rx Timer Cap helps train our internal clocks as to when it is time to take the next medication,” comments Richard Burke Jr., founder and president of Rx Timer Cap LLC.

Thrifty White also recently introduced the HealthyPackRx, in which patients get a box containing 30-day supplies of all their maintenance medications — organized into individual packages labeled with the medication, date and time to be taken.