** Shares of Nectar Lifesciences NECT.NS slump 20% to 18.50 rupees, their lowest level since June 2023
** Drugmaker sells API business for 12.7 bln rupees ($148 mln) and menthol business for 200 mln rupees to Ceph Lifesciences
** NECT says proceeds to repay debt, improve financial position, and invest in newer businesses
** Trading volume at nearly 29 mln shares so far, 19x 30-day avg volume
** Stock down nearly 53% YTD
($1 = 85.6520 Indian rupees)
(Reporting by Nandan Mandayam in Bengaluru)
((Nandan.Mandayam@thomsonreuters.com; Mobile: +91 9591011727;))