Feb 2 (Reuters) - AbbVie Inc beat Wall Street estimates for fourth-quarter profit on Friday, helped by a smaller-than-expected decline in sales of its blockbuster drug, Humira, and strong demand for Botox amid stiff competition.

Investors have been keeping a close eye on falling sales of arthritis drug Humira, which was until recently the world's top-selling treatment. More than half a dozen biosimilars hit the U.S. market over the last year, hurting the drug's sales.

Humira's sales fell 41% to $3.30 billion in the fourth quarter, but beat estimates of $3.28 billion. Its U.S. sales plunged 35% to $12.16 billion in 2023.

Humira sales also fell less than expected in the third quarter as it maintained favorable positions on insurance drug coverage lists, but a large pharmacy benefit manager, CVS Health , said last month it will remove the drug from some of its lists.

AbbVie has been counting on newer immunology products Skyrizi and Rinvoq to help fill Humira's sales decline. On Friday, AbbVie raised its 2027 forecast for sales of the two drugs to $27 billion, from $21 billion earlier.

For 2024, AbbVie forecast an adjusted profit in the range of $11.05 to $11.25 per share. Analysts on average were expecting a profit of $11.24, according to LSEG data.

The outlook includes a 32 cent hit from its acquisitions of drug developers ImmunoGen and Cerevel Therapeutics last year.

Rinvoq sales of $1.26 billion beat expectations of $1.17 billion, while Skyrizi sales of $2.39 billion were in line with estimates.

Botox brought in sales of $1.49 billion, ahead of combined estimates of $1.43 billion.

Botox has been facing increased competition from newer anti-wrinkle injections from Revance Therapeutics, Evolus and others.

AbbVie reported a quarterly adjusted profit of $2.79 per share, beating estimates by 2 cents. (Reporting by Leroy Leo in Bengaluru; Editing by Maju Samuel)