Privacy and security are critical requirements for using patient profiles in distributed healthcare environments. The amalgamation of new information technology with traditional healthcare workflows for sharing patient profiles has made the entire system vulnerable to security and privacy breaches. In this paper we present a novel access control model based on a framework designed for data and service interoperability in the healthcare domain. The proposed model for customizable access control captures the dynamic behavior of the user and determines access rights accordingly. The model is generic and flexible in the sense that an access control engine dynamically receives security effective factors from the subject user, and identifies the privilege level in accessing clinical data using different specialized components within the engine. Standard data representation formats are used to make the model compatible with different healthcare environments. The access control engine uses a flow-based approach to follow the user's behavior. The proposed model is supported by a real world case study.