The Food and Drug Administration announced yesterday that it intends to ban the labeling and marketing of nonprescription drugs as daytime sedatives.

FDA Commissioner Donald Kennedy said there is no medical justification for the drugs and they are a potential danger because users can become drowsy while driving or using other dangerous machines.

The largest selling daytime sedatives are Compoz, Cope, Miles Nervine, Tranquium and Quiet World. Consumers spend about $7 million annually on daytime sedatives.

The action planned by FDA would not necessarily result in removal of these sedatives from the market, but would force a change in their labeling and in the way they are advertised.

The manufacturers could continue to sell the products if they ceased describing them as daytime sedatives or in other ways that the FDA considered misleading.

An FDA spokesman said it has not been decided whether manufacturers could keep the same brand names should they continue to market the drugs, but the FDA generally allows the retention of trade names in such cases.

Kennedy, in testimony to Sen. Gaylord Nelson's (D-Wis.) Subcommittee on Monopoly and Anticompetitive Activities, said there is no evidence that the daytime sedatives lessen anxiety or provide any medical benefit.

The FDA will publish its intended restrictions this fall and a spokesman said that after public comment the restrictions could be expected to go into effect in mid-1978.

The FDA move against the sedatives is unrelated to charges that an antihistamine used in them may cause cancer.

Kennedy said he has asked the National Cancer Institute to speed up its study of the possible connection between the antihistamine, methapyrilene, and cancer. The FDA has not concluded whether such a connection exists, a spokesman said.

Methapyrilene also is used in sleep aids and in many cough and cold remedies.

Dr. William Lijinsky of Maryland's Frederick Cancer Research Center testified last week that the antihistamine may mix with nitrite in the stomach to form a carcinogenic substance.

Lijinsky told Nelson's subcommittee that 30 per cent of rats given the combination in his experiments got liver cancer.