Philadelphia police are investigating the death six months ago of a University of Pennsylvania student after Tylenol capsules found in his closet were determined yesterday to contain cyanide.

At the same time, concern about recent cases of poisoning of Tylenol capsules continued throughout the country as health agency switchboards were flooded with telephone calls from persons complaining they had been taken ill after swallowing Tylenol.

Reports of mysterious deaths in Tennessee and Kansas proved not to be related to Tylenol, according to health officials.

Seven persons were found dead last week in Chicago after they had taken Tylenol laced with cyanide, and police yesterday continued searching for the persons or persons believed responsible.

Philadelphia police announced last night that they have reopened the case of William Pascual, 26, a graduate student at the university's Wharton School of Finance and Commerce, whose death last April 3 was ruled a suicide.

Police now say they believe his death was caused by cyanide in capsules of Extra-Strength Tylenol.

Pascual, a 1972 graduate of Gonzaga High School here and a former resident of Silver Spring, had been found dead in his bedroom by his wife after a party, with a suicide note addressed to his mother, Detty, in Arlington.

Pascual had emptied all of his bank accounts before he died, according to Frank Scafidi, chief of Philadelphia police homicide division.

Last April, the Philadelphia medical examiner said Pascual died from ingesting cyanide, which was found in his stomach and blood.

Scafidi said it is not known if Pascual had ingested any of the Tylenol capsules from the bottle. Homicide Capt. Gerald Kane said the original autopsy showed no Tylenol in Pascual's body.

It was not known whether another autopsy will be performed after a Philadelphia funeral home spokesman said, pending a check of records today, the body may have been cremated.

A bottle of Extra-Strength Tylenol, bearing lot number FE7603 with an expiration date of June, 1983, was found in a shoe in a closed closet in the bedroom, Scafidi said.

He said that initial tests on three capsules in April were negative but that after news of the Chicago poisonings, police reexamined the nine remaining capsules, which had coagulated into a mass, and found traces of cyanide in several.

Scafidi said the Philadelphia police department "now has a great deal of a investigating to do . . . as to the use of Extra-Strength Tylenol" in the Philadelphia area.

Across the nation, so many Californians complaining of Tylenol poisoning jammed government health office telephones that state and federal officials said they were unable to respond to more than a few calls.

The Tylenol panic hit Californians more forcefully after a lethal dose of strychnine was discovered in Tylenol tablets that Greg Blagg, 27, a butcher in Oroville, Calif., said had made him violently ill. His sickness is being investigated.

A federal Food and Drug Administration official said yesterday, however, that one capsule from the bottle Blagg said he used contained only 2.4 milligrams of strychnine mixed with a starchy substance such as that found in rat poison.

FDA officials said that dose should not make an average adult sick, although how much strychnine might have been in the Tylenol taken by Blagg is unclear.

A lethal dose of strychnine is estimated to be between 75 and 200 milligrams, authorities said.

Blagg, in an hour-long news conference Tuesday night, said he vomited, experienced stomach and muscle cramps and briefly lost consciousness within about an hour after taking three Tylenol capsules for a headache on the afternoon of Sept. 30.

Neither Blagg nor his attorney, Joseph VanDervoort, could be reached for comment yesterday.

Other cases of suspected Tylenol poisoning around the country turned up negative yesterday, as have others all week.

A truck driver who died suddenly in Tiptonville, Tenn., after making a delivery Tuesday, had Tylenol capsules in a package with him, but tests yesterday showed no cyanide or strychnine in the capsules, an FDA spokesman said.

The body of a 30-year-old woman in Wichita found dead with Tylenol is being autopsied, but an FDA spokesman said the empty bottle of Tylenol capsules found near her body contained a residue of powder that contained no cyanide.

Concern has extended beyond Tylenol to other brands of pain-killing products and even totally unrelated products sold in unsealed capsules or packages.

David Graves, a pharmacist with the poison control center in Minneapolis, said that while most of his calls -- double the usual number -- concern Tylenol, he has taken at least three calls about vitamin C capsules and many about other products with unsealed packages.

A spokesman for Walgreen's drug store chain said a national sampling showed a decrease in sales of pain-relievers.

An Osco Drug Co. spokesman said, "Right now, I think our customers in general are being cautious for all products."

In another development, Health and Human Services Secretary Richard S. Schweiker said he has ordered the FDA to begin drafting a new drug packaging regulation.

"It's important to understand that even if we come up with a regulation fairly soon . . . it's still going to take the industry three to four months to get this equipment in place," he said.

An FDA spokesman said that FDA will rely on the industry task force set up last week by the Proprietary Association, the trade association of the over-the-counter drug industry, to supply expertise on packaging in drafting the new regulations.

Robert Kniffin, a spokesman for Johnson & Johnson, whose subsidiary McNeil Consumer Products Co. manufactures Tylenol, said regardless of any other actions, "There will certainly be a change in Tylenol packaging. That is definite."