The proposed offer, which would value the London-listed maker of skin lifting, collagen stimulation treatments and dermal fillers at roughly 161.2 million pounds ($205.6 million), comes after three deadline extensions for Huadong to make a bid.
Shares of Sinclair ended 1.3 percent higher at 20.05 pence.
Huadong has also agreed to announce a firm intention to make an offer for Sinclair before Oct. 2, ahead of the Oct. 5 deadline under UK takeover rules.
Sinclair has gained 8.2 percent in market value since early July, when Huadong first confirmed it had made an approach.
It is intended that the offer, if made, would be structured as a recommended offer to be implemented by way of a scheme of arrangement, the companies said on Tuesday.
“Sinclair independent directors are of the view that the possible offer is an attractive proposal which they would be prepared to recommend to Sinclair shareholders,” the British company said.
($1 = 0.7841 pounds)
(Corrects Aug 28 item to drop reference to shares erasing gains in paragraph 3 as the news on potential offer came after trading hours)
Reporting by Muvija M in Bengaluru; Editing by David Goodman