LOS ANGELES – The city that popularized the fast food drive-thru has a new innovation: 24-hour medical marijuana vending machines.

Patients suffering from chronic pain, loss of appetite and other ailments that marijuana is said to alleviate can get their pot with a dose of convenience at the Herbal Nutrition Center, where a large machine will dole out the drug around the clock.

“Convenient access, lower prices, safety, anonymity,” inventor and owner Vincent Mehdizadeh said, extolling the benefits of the machine.

But federal drug agents say the invention may need unplugging.

“Somebody owns (it), it’s on a property and somebody fills it,” said DEA Special Agent Jose Martinez. “Once we find out where it’s at, we’ll look into it and see if they’re violating laws.”

At least three dispensaries in the city, including two belonging to Mehdizadeh, have installed vending machines to distribute the drug to people who carry cards authorizing marijuana use.

Mehdizadeh said he spent seven months to develop and patent the black, armored box, which he calls the “PVM,” or prescription vending machine.

A sliding fence protects the tinted windows of his dispensary, barely distinguishing it from a busy thoroughfare of strip malls, automobile dealers and furniture shops. A box resembling a large refrigerator stands inside the nearly empty shop, near a few shelves stocked with vitamins and herbs.

A guard in a black T-shirt emblazoned with the word “Security” on the front stands at the door. A poster of Bob Marley decorates a back room.

The computerized machine requires fingerprint identification and a prepaid card with a magnetic stripe. Once the card and fingerprint are verified, a bright green envelope with the pot drops down a slot.

Mehdizadeh says any user approved for medical marijuana and registered in a computer database at his dispensaries can pre-purchase the drug and then use the machine to pick up.

The process provides convenience and privacy for users who may otherwise feel uncomfortable about buying marijuana, Mehdizadeh said.

At the Timothy Leary Medical Dispensary in the San Fernando Valley, the vending machine is accessible only during business hours. An employee there said the machine was introduced about five months ago, and provides speedy service.

“It helps a lot of patients who are in a lot of pain and don’t want to wait around to get help,” Robert Schwartz said. “It’s been working out great.”