NORTHAMPTON — A Vermont man is being held on $50,000 bail on charges that he physically assaulted a Massachusetts state trooper after a traffic stop on Interstate 91.

Darryl Kittredge, of St. Johnsbury, pleaded not guilty Tuesday in Hampshire Superior Court to charges of assault and battery causing serious bodily injury, assault and battery on a public employee, possession of cocaine and possession of a Class E drug (dexmethylphenidate hydrochloride).

The drug is a central nervous system stimulant used in the treatment of attention deficit hyperactivity disorder (ADHD.)

The incident allegedly occurred March 1 on I-91 near the Northampton-Hatfield line.

Trooper Matthew Mielke pulled over a gray Nissan Maxima shortly before 8 p.m. after observing a defective right license plate light on the car, according to Northampton District Court documents.

Before stopping, Kittredge was allegedly observed ducking down repeatedly, according to court documents. After he pulled over, Mielke ordered Kittredge out of the car so he could search him.

As Mielke tried to handcuff Kittredge, he allegedly spun toward the trooper and struck his right forearm, causing a scrape to the arm, according to court documents.

Kittredge then allegedly stepped on Mielke’s right foot near his Achilles tendon.

“Immediately, Trooper Mielke felt a sharp pain in his Achilles nearly causing him to fall onto the ground,” court documents state. “Trooper Mielke knew immediately that his Achilles was most likely ruptured completely.”

Kittredge ran from the scene and was found less than a mile away in a barn on West Street.

Mielke was taken to Baystate Medical Center where he was treated, discharged and referred to an orthopedic surgeon.

A bail review hearing is scheduled for Aug. 23. Kittredge has been in the Hampshire County Jail and House of Correction since his arraignment in district court.