May 7 (Reuters) - Privately held contract manufacturer

Future Pak said on Tuesday it will sweeten its buyout offer for

Vanda Pharmaceuticals ( VNDA ) to include contingent value

rights, in addition to the proposed offer price of $7.25 to

$7.75 per share in cash for the drugmaker.

The rights would provide additional benefits to Vanda

shareholders if certain performance targets are met.

Future Pak said the revised offer includes up to $260

million of potential contingent value rights or CVR payments and

represents up to $4.37 per share in additional value for Vanda.

Vanda did not immediately respond to a request for comment.

Shares of the drugmaker rose 6% to $5.14 in premarket

trading.