First Lady Nancy Reagan's drug abuse "summit" with the wives of 29 world leaders in town for the United Nations' 40th-anniversary commemoration took some unexpected turns today.

One came in a face-to-face appeal from the wife of Nicaragua's President Daniel Ortega, whom President Reagan has called "the little dictator who went to Moscow in his green fatigues," to find "a better understanding and work towards better relationship between our two countries."

The other was a proposal from the wife of Sri Lanka's Prime Minister Ranasinghe Premadasa that the first ladies' next get-together on international drug problems take place in a developing country.

Both came after the end of the official proceedings, a 2 1/2-hour series of speakers with no open discussion.

Talking to reporters later, Mrs. Reagan said she told Rosario Maria Murillo, Nicaragua's first lady, that she shares the hope that the United States and Nicaragua will have a better relationship: "I said I hoped so too, I hope we all have better relations."

Of Hema Premadasa's suggestion, Mrs. Reagan, who has made a point of visiting drug treatment centers in her trips abroad with the president, said she told her "we would think about it.

"I think the problem may be that we've been in this fight a little bit longer and therefore maybe we're in a position to show them and give them information and let them see people that they haven't seen or wouldn't be able to see if they went somewhere else."

She added, "The whole idea is to try to let other people benefit by our mistakes so they don't go through all that we went through."

Premadasa made her proposal as the first ladies were starting to leave the U.N. conference room, in which non-English-speaking conferees had listened to simultaneous translations of the proceedings. There was immediate support from several other wives as they reassembled in a preluncheon reception.

Premadasa said her proposal wasn't premeditated -- "I just suddenly thought of it." She said her country has a serious drug problem and that she felt the group should have another meeting, but in an Asian country. "This was an invitation to a conference of this nature to voice our grievances, too," she said.

Although an aide to Mrs. Reagan said later it was "natural" that the women would want to meet again, the idea of meeting in a Third World nation seemed to catch the White House by surprise.

The White House has kept tight control of Mrs. Reagan's campaign against drug abuse since she launched it 3 1/2 years ago. Her aides have called the shots on her drug abuse dialogues here and abroad, and they carefully orchestrated her April conference at the White House when 17 first ladies joined her, just as they did the one today. They have taken particular care to avoid anything that might bring international political repercussions.

In fact, in her opening remarks today, Mrs. Reagan said, "Being a nonpolitical meeting, we cannot change laws, but on a mother-to-mother basis we can begin plans for work at home."

Instead of the open discussions that marked the April session, today's program consisted entirely of prepared speeches, primarily from U.S. officials and leaders in private U.S. drug programs. The first ladies were asked to prepare written statements for today's meeting and have their U.N. missions distribute them to interested parties.

"It was only because of time constraints," said Elaine Crispen, Mrs. Reagan's press secretary.

Asked at the reception about meeting in a developing country, the wives of leaders of Greece, the Philippines, Jordan, Pakistan, Cyprus and Nicaragua all expressed approval.

"It would be nice to have a conference elsewhere now that it's been held twice in the United States," said American-born Margarita Papandreou of Greece, who did not attend the April conference. "Other possible proposals can be made."

Pakistan's Begum Shafiq-ul-Haq Zia said she felt strongly about holding a conference in a developing country where drug use can be studied "in the context of poverty -- how they interact and go hand in hand with each other."

Imelda Marcos of the Philippines called Sri Lanka's proposal "a very logical course." She quickly expressed admiration for Mrs. Reagan's "enlightened" program and commended American leadership in it.

"As we always say in the Philippines, a program like this to be led by the United States is very important," she said. "While Americans cannot solve the major problems, no major problems can be solved without America."

Jordan's American-born Queen Noor said she was struck by the need that perhaps now is an opportunity "for input from other countries." She said Jordan has no significant drug problem yet but that she already sees the "seeds and signs of what might be a potential problem."

Nicaragua's Murillo said categorically there is no drug problem in her country, but that it's an international concern that must be analyzed and acted upon.

"We used to have a drug problem before the revolution," she said. "Especially between middle-class students and young people that came back from other countries where they studied."

She said since the revolution drugs no longer have been a social problem, and that she believes it is Nicaragua's Marxist form of government that has made the difference.

Would she propose at a drug abuse conference that other countries change their forms of government?

"I think we should find ways of reaching in every society a life that has a purpose, a commitment, makes us feel active and doing something for somebody," she answered.

Cyprus' Erasmia Kyprianou said no drug problem yet exists in her country either. "Fortunately we have very strong family links. But one never knows what is coming."

The White House drew up its conference list by inviting wives of world leaders planning to attend this week's U.N. commemoration. The session featured talks by Carlton E. Turner, deputy assistant to the president for drug abuse policy, and Jon Thomas, assistant secretary of state for international narcotics matters. Speakers from the private sectors of drug abuse prevention, education and rehabilitation were Dr. Marsha Schuchard, founder of Parents Resource Institute on Drug Education; Dr. Mitchell Rosenthal, president of the international drug rehabilitation center Phoenix House, and Tom Adams, vice president of Pacific Institute, who is involved in "The Just Say 'No' Movement."

Portugal's Maria Manuela Eanes gave the representative "First Ladies' Report" on progress since the April conference. Three former drug users -- from West Germany, Great Britain and the United Stated -- described their personal experiences while on drugs. When Anita Jones, 20, completed her story of how she began using drugs at age 13 and became an unwed mother at 16, she turned to Nancy Reagan, who put her arms about her and kissed her.

Sharing the podium with Mrs. Reagan was Marcella Perez de Cuellar, wife of the U.N. secretary general. She said her husband recently called for a worldwide conference on drugs.