Soumitra Chatterjee is not responding to treatment and his platelet count has dropped further in the last 24 hours, a doctor at the hospital said.
Though Soumitra Chatterjee's organs were functioning 'well', the platelet count has dropped and the level of urea and sodium in his blood has gone up, said Dr Arindam Kar.
The doctor said since Chatterjee has been in ICU for three weeks, "it is always challenging to prevent secondary complications."
Yash-starrer KGF became a huge hit across the country when it first released in 2018.
Soumitra Chatterjee tested negative for COVID-19 last week. His condition has been improving but a sudden deterioration, mainly the neurological issues, was detected on Tuesday.
Dhruva Sarja, brother-in-law of Meghana Raj, took to Instagram to announce the birth of his nephew.
Though Soumitra Chatterjee's oxygen saturation is adequate, doctors are concerned about his involuntary movement, agitation and restlessness.
Bheemasena Nalamaharaja stars Aravinnd Iyer, Aarohi Narayan, Priyanka Thimmesh, and Achyuth Kumar. It will start streaming on Amazon Prime Video from October 29.
"The only problem is Covid encephalopathy which is sub-normal. Another couple of days of being administered steroids, he will bounce back to improvement," the attending doctor said.
Bheemasena Nalamaharaja, starring Aravinnd Iyer, Aarohi Narayan, Priyanka Thimmesh, Achyuth Kumar and Aadya, will premiere on Amazon Prime Video on October 29.
Soumitra Chatterjee tested negative for the infection on October 14, after which he was shifted to a non-COVID ITU for treatment.
Soumitra Chatterjee, who has the rare distinction of having worked with maestros like Satyajit Ray, Mrinal Sen, Tapan Sinha and Tarun Mazumdar, was admitted to the hospital here on October 6 after he tested positive for COVID-19.
Soumitra Chatterjee is speaking a bit as well as recognising people and identifying their voices, a doctor treating him at a private hospital said.
Soumitra Chatterjee's oxygen saturation has also improved while his sodium and potassium have been both corrected, doctors, treating him at the city-based private hospital, said.
Soumitra Chatterjee, who tested negative for coronavirus on Wednesday, was administered "musical therapy" and physiotherapy on Thursday, a doctor said.
Actor Soumitra Chatterjee had no fever since Tuesday evening but is still in an "acute confusional state."
Veteran actor Soumitra Chatterjee was admitted to hospital on October 6 after he tested positive for COVID-19.
Rajan and his brother Nagendra, who passed away at 65 in 2000, had a successful career as music directors from early-1950s to the late 1990s.
Soumitra Chatterjee was given plasma therapy twice on Saturday and the octogenarian also underwent a CT scan.
Vijay Reddy left a deep imprint on movie buffs with his films Gandhada Gudi, Bhakta Prahlada and Na Ninna Mareyalare.
Soumitra Chatterjee was at an "acute confusional stage" following which the neurologist advised him to be shifted to the ITU, he said.
The story of KGF is set in the backdrop of 1980s India. It follows the journey of an orphan boy in the quest for power and wealth.
In the last two months, Soumitra Chatterjee had been shooting for a biopic and a documentary on his life.
Rockline Sudhakar made his acting debut in a minor role in the film Belli Modagalu in 1992. He wen on to act in over 200 movies in Kannada including Pancharangi, Paramathma, Drama, Mr and Mrs Ramachari, Love In Mandya and Vaastu Prakara.