International Physicians for the Prevention of Nuclear War, a worldwide federation of doctors and health professionals founded five years ago to publicize the dangers of nuclear weapons, was awarded the 1985 Nobel Peace Prize today.

The antinuclear group, with more than 145,000 members from 40 nations, was honored for its "considerable service to mankind by spreading authoritative information and by creating an awareness of the catastrophic consequences of atomic warfare," the Norwegian Nobel Committee said in its announcement.

The prize, worth $224,000 this year, carries inestimable prestige. A record number of 99 candidates were considered for the award this year. Previous winners include Mother Teresa, Solidarity leader Lech Walesa of Poland, and Anglican Bishop Desmond Tutu of South Africa.

Egil Aarvik, chairman of the five-man selection panel, said "particular importance" was attached to the fact that the organization, known informally as Doctors Against Nuclear War, evolved out of a joint initiative by medical professionals in the United States and the Soviet Union.

The federation was founded by two leading heart specialists, Dr. Bernard Lown of the Harvard School of Public Health and Dr. Yevgeni Chazov of the Soviet Union's Cardiological Institute.

Chazov, the Soviet Union's most prominent cardiologist, was the personal physician of Soviet leaders Leonid Brezhnev, Yuri Andropov and Konstantin Chernenko, and he has been a highly influential spokesman for the nuclear freeze movement.

He has been a member of the Communist Party since 1962.

Lown and Chazov found that they collaborated so well in medical research that they decided to extend their common work to enlist other doctors in the struggle to abolish nuclear weapons.

A formal exchange of letters between the two longtime friends and associates provided the catalyst that led to the creation of the organization by six American and Soviet physicians, who met in Geneva in 1980 to forge a consensus on how to express their views despite conflicting political systems.

The physicians drew up four guidelines to govern the group's work: They agreed to restrict their focus to nuclear war, to work to prevent such a conflict in keeping with professional vows to protect life and preserve health, to circulate the same factual information and to avoid taking positions on specific policies of any government.

Aarvik said the committee intended to invite Lown, 64, and Chazov, 56, to receive the prize on behalf of their organization at award ceremonies in December. Both men share the title of president of the group, which has its headquarters in Boston.

Aarvik noted that the Soviet Union has boycotted Nobel ceremonies ever since the Peace Prize was bestowed on dissident physicist Andrei Sakharov in 1975. Sakharov is now living in internal exile in Gorki, 250 miles east of Moscow, and is reported to be in poor health.

"It remains to be seen," Aarvik said when asked if he thought Chazov would be allowed to attend. However, Nobel Committee sources said it was apparent that Chazov's leading role in the doctors' campaign clearly enjoyed the blessing of his government and that his presence at the award ceremony was highly probable.

The Soviet press promptly reported today's award, indicating Soviet pleasure that Chazov had been honored, Reuter reported from Moscow.

In Geneva, where they were attending the fifth anniversary of their group's founding, Lown and Chazov embraced and said they were "overwhelmed, surprised and excited" by the award.

"We physicians have a medical prescription: stop all nuclear explosions," Lown said. He urged President Reagan to take up the Soviet Union's offer of a nuclear test ban.

"The ball is now in Reagan's court," Lown said. "There is no reason for not stopping nuclear explosions now. We as physicians urge it as a prime priority."

Chazov said the prize is "recognition of the contribution made by our movement. It is also recognition of the correctness of our ideas."

The two said all the prize money would be used for the furtherance of the organization.

Some participants in the Geneva meeting, who asked not to be named, told special correspondent John Parry that the original idea of getting the medical profession involved in a nuclear test ban came from Dr. Howard Hiatt, former dean of the Harvard School of Public Health, now a professor at Harvard Medical School, and they expressed the hope that he would be in some way associated with the award.

The Nobel Committee said the doctors' antinuclear campaign was particularly effective because its respected scientific work has "contributed to an increase in the pressure of public opposition to the proliferation of the atomic weapons and to a redefining of priorities, with greater attention being paid to health and other humanitarian issues."

Aarvik said the award citation was not intended to demean the sincerity and good will of other antinuclear groups. But he stressed that the efforts by the doctors have proved more significant because "their work is based on solid scientific evidence rather than pure emotion."

The committee also noted that the "awakening of public opinion" by the organization's global impact "can give the present arms limitation negotiations in Geneva new perspective and a new seriousness."

The cooperation shown by medical authorities in the United States and the Soviet Union, along with the rest of the world, provides an admirable example for politicans and diplomats, Aarvik said in the interview.

"If this prize has any message, it is to say to the American and Soviet negotiators in Geneva that it is very important that they come up with a successful result," Aarvik, a former president of the Norwegian parliament, said. "All people in the world are keen to see disarmament become a reality, and this peace prize underlines the significance of the Geneva talks."

As established by the will of Alfred Nobel, a Swedish industrialist and the inventor of dynamite, the peace prize is awarded "to the person who shall have done the most or the best work for fraternity between nations, for the abolition or reduction of standing armies and for the holding and promotion of peace congresses."

Those who choose the peace prize winners are appointed by the Norwegian parliament for terms of six years. The current committee consists of two former heads of parliament, a writer, a historian and a priest.