The Narcotics Control Bureau has summoned Dharma Productions director and executive producer Kshitij Ravi Prasad for joining the investigations into the drugs cases linked to film personalities being probed by the agency, officials said here on Thursday.Raviprasad is expected to visit the NCB offices on Friday for questioning into one of the drug-related cases pertaining to the death of actor Sushant Singh Rajput.An NCB official confirmed that there has been no raid at the office or home of Kshitij Ravi Prasad, as reported in some sections of the media.Dharma Productions is owned by prominent Bollywood filmmaker Karan Johar.