Potomac Electric Power Co. has announced several executive changes that, according to the company, are designed to improve its ability to serve and communicate with customers and shareholders.

James S. Culp, presently vice president of customer services, has been named vice president of investor relations, responsible for shareholder services and communications with investors and the professional investment community.

John M. Derrick Jr. succeeds Culp as director of customer services with responsibility for all customer billing and credit operations. He was previously manager of consumer engineering.

Sharon Pratt Dison, formerly an associate general consel, has been named director of consumer affairs with primary responsibility for indentifying the needs of consumers and developing appropriate plans and policies.

David H. Byce has been appointed director of corporate affairs, the organization responsible for public relations and corporate internal c/mmunications.

Stuart E. Karu has been elected president and chief executive officer of the communications firm of Henry J. Kaufman & Associates.

Karu has been with Kaufman for seven years and was named executive vice president last year. He organized and developed the Kaufman subsidiary, the Market Research Bureau, which has become a major supplier of market research in the Washington-Baltimore area.

Claudine B. Malone has been named to the board of directors of Dart Drug Corp.

Malone is an associate professor of business administation at Harvard Business School. She teaches management education seminars and works as a consultant to several corporations. She is a member of the editorial board of the Harvard Business Review; a member of the corporations of Babson College and the Dana Hall School; a former member of the Erisa Advisory Council to the Department of Labor; a director of the Scott Paper Co., the Campbell Soup Co., the Boston Co., Supermarkets General, and the Penn Mutual Life Insurance Co.

Louis M. Thompson Jr. and Don R. Slatton have been named senior staff vice presidents of the 112,000-member National Association of Home Builders. Thompson will oversee the operations of three major divisions; public affairs, economics and publications. Slatton will direct NAHB's conventions and meetings, association services and builder services divisions.

Thompson, an assistant White House press secretary during the Ford administration, has served as the association's staff vice president for public affairs for the past year.

Slatton has been NAHB staff vice president for association services since 1977. Before that, he was executive vice president of the Alabama Home Builders Association.

Dr. Nathan A. Baily has been appointed senior staff vice president, education, for the Mortgage Bankers Association of America.

Baily was the founding dean and professor of management of the School of Business Administration of American University.