Valeant Pharmaceuticals has bumped up its offer for Allergan by 21% in the hope of finally pulling the Botox maker under its wing.

The group has not only increased its cash consideration by $10 a share to $58.30, but has also added a new Contingent Value Right relating to sales of Allergan's experimental eye drug DARPin.

This CVR, it says, would provide up to around $25.00 per share of additional value, based on estimated 10-year sales of $20 billion for the drug.

As before, Allergan shareholders would also get 0.83 of a Valeant share for each Allergan share, reportedly giving the deal a total value of around $49.4 billion.

"Our increased offer provides additional immediate value to the Allergan shareholders -- we note that the cash portion of our revised offer alone represents approximately 50% of Allergan's unaffected share price -- and provides Allergan shareholders with significant substantial additional value if DARPin achieves Allergan's expectations," Valeant said in a statement. 

But both companies saw their stock slip as details of the sweetened bid emerged and fell shy of expectations.

"I was actually surprised (Valeant) didn't go higher," said David Amsellem, analyst at Piper Jaffray, reports Reuters. "Clearly they are going to continue to be aggressive, making a full-court press to get this done".

Allergan has confirmed receipt of the bid and said it would "carefully review and consider the revised proposal".

Nestle deal

Meanwhile, Valeant also announced the sale of its filler and toxin assets to Nestle for a cash deal worth $1.4 billion.

The move, which gives Nestle commercial rights to Restylane, Perlane, Emervel, Sculptra, and Dysport, could help overcome any competition issues in Valeant's proposed takeover of Allergan, industry observers note.