When Bonnie Zaruca lost drug coverage in January, the Sylvania resident started paying several times more at Kroger for a 90-day supply of her only prescription.

Still, it wasn't until Kroger's price for generic Ambien sleep medication recently took a $5 jump to $139.59 that Ms. Zaruca decided to comparison-shop. She called Costco, and the same 90-day prescription -- for 5 mg of zolpidem tartrate -- cost $14.41 for nonmembers and $10.72 for members.

Ms. Zaruca went to Costco to get a printout to confirm the prices. And the convenience of getting her prescription at Kroger was no longer worth more than $500 a year.

"The point is, you have to check around," Ms. Zaruca said. "I knew I might be paying more, but I had no idea it would be that much."

The experience prompted a price comparison by The Blade of six common prescription medications, including zolpidem tartrate, at eight Toledo-area chain pharmacies for customers paying up front without any insurance, prescription savings plans, or memberships.

The survey found that Walgreens, not Kroger, was the highest on that medication, while Kroger, Meijer, and Giant Eagle dispensed at no cost one of the other prescriptions in the comparison, 28 caplets for the antibiotic amoxicillin.

Kroger spokesman Jackie Siekmann said the chain does not discuss how prices are decided. But there is a direct correlation with prices Kroger can negotiate with pharmaceutical manufacturers, she said.

There were wide price variations with other chains too. Each had instances where it was on the low end of pricing for one of the medications but on the high end for others, although the generic Ambien sleep medication had the widest spread in the comparison primarily involving 30-day supplies.

Costco, for example, was the lowest for three of the medications, including the only name-brand drug that was compared, Lipitor.

All six prescriptions compared by The Blade were in IMS Health Inc.'s list of the top 20 medications dispensed nationwide annually. The drugs are used to treat various common ailments, including diabetes and high blood pressure.

Hydrocodone/acetaminophen, a narcotic painkiller better known as Vicodin, is by far the most common prescription dispensed nationwide, according to the IMS Health report.

Chains may be trying to balance out their highly touted low-cost and free prescriptions -- a 30-day supply of the generic diabetes drug metformin HCL, for example, costs $4 at Kroger, Walmart, and Target and is free at Meijer and Giant Eagle -- or have the ability to negotiate better deals for some products but not others, said C. Britt Beemer, chairman and chief executive officer of America's Research Group, which studies consumer behavior.

Even those with prescription drug coverage should compare prices, he said.

"It pays to be a comparison shopper," Mr. Beemer said. "In this day and age, you're foolish if you don't do comparison shopping."

Just as forgoing name-brand medications for generics if they are effective is a wise move, obtaining 90-day supplies of maintenance drugs for diabetes and other chronic conditions also may save money.

People with multiple prescriptions may even be better off getting prescriptions at different stores if savings are significant, Ms. Zaruca said.

A former pharmaceutical company representative who was laid off from that job in 2009 but has since found other employment, Ms. Zaruca said she discussed with doctors the importance of telling patients to shop around, which is especially important if one is on multiple or high-frequency medications.

"What are the chances I stumbled on the one drug that had that big of a price difference?" Ms. Zaruca said. "If they can get customers to pay that, they're going to charge it."

Rite Aid, however, advises shoppers to find the lowest overall price for medications if cost is important and get them all at the same place. That way, the pharmacist is aware of all of the drugs they are taking and can check for interactions, said Ashley Flower, Rite Aid Corp. spokesman.

The pharmacy chain continues to evaluate prices and monitor competitors to make sure it is in line, but a number of factors -- store locations, utilities, overhead, and services -- go into determining how much customers are charged, she said.

"We do go to great lengths to make sure we price competitively," Ms. Flower said.

In The Blade's comparison, Rite Aid was the highest or near that mark for all but one prescription, the generic Ambien.

Yet Rite Aid stores in both Ohio and Michigan will match verifiable prices of competitors such as Walmart, which, for example, offers a 30-day supply of the generic blood pressure medication lisinopril for $4, Ms. Flower said.

Rite Aid, however, does not match free offers, she said.

Plus, all Rite Aid stores have free prescription savings cards, through which customers can get more than 500 generic medications for $8.99 for a 30-day supply and $15.99 for a 90-day supply.

The free card also offers a 20 percent discount on all other generic and brand-name prescriptions and other perks.

Walgreens also was on the high side of compared medication and has a prescription savings club, for which it charges $20 a year for individuals and $35 for families.

More than 8,000 brand-name and generic medications are covered by the program, including more than 400 generics priced at $12 for a 90-day supply.

Lipitor, for example, would cost $142.99 for a 30-day supply of 10 mg pills, but the prescription program would cut the price by $23, a Walgreens pharmacy employee at the 1330 North Reynolds Rd. location said.

Contact Julie M. McKinnon at: jmckinnon@theblade.com or 419-724-6087.

First Published November 6, 2011, 4:07 a.m.