For the past couple of years, investors looked ahead to one particular thing with dread: AbbVie's (ABBV -0.50%) blockbuster immunology drug facing competition. After all, at its peak, Humira brought in almost $21 billion in annual sales, and the treatment helped AbbVie grow revenue and deliver dividend growth over time. So it's logical to wonder whether, today, considering the Humira situation, you should think twice before buying AbbVie.

And you're not the only one. So far this year, AbbVie shares have slipped about 15%. But before turning our backs on this pharmaceutical stock, let's take a closer look at how the revenue situation is evolving -- and find out whether the share price decline is a warning of more to come, or an excellent buying opportunity for investors seeking earnings and dividend growth.

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A few quarters in to Humira's loss of exclusivity

We're now seen a few quarters of Humira facing competition, and things don't look as bad as we could have initially imagined. In the third quarter, Humira sales fell about 36% to $3.5 billion, about in line with expectations in the U.S. market and better than expectations internationally.

That's positive because the movement is somewhat gradual, making it easier for AbbVie to transition into its post-Humira story. And here's where we get to the really good news: AbbVie has been grooming two other candidates -- now approved in several indications -- to take over where Humira leaves off. I'm talking about newer immunology drugs Skyrizi and Rinvoq, forecast to, together, generate more than $21 billion in revenue by 2027. So if all goes well, these drugs will surpass Humira's peak sales.

Now, here's the best news. In the quarter, Skyrizi and Rinvoq showed they have what it takes to reach that goal. Here are some clues. First, Skyrizi and Rinvoq are on track to deliver more than $11 billion combined in revenue this year after their sales rose 52% and 59%, respectively, in the recent quarter.

Skyrizi has become a market leader in psoriasis treatment and is quickly gaining ground in Crohn's disease. In fact, AbbVie hopes its recent study showing stronger Skyrizi efficacy compared to market giant Stelara will lead to additional market share in Crohn's.

As for Rinvoq, in the most recent quarter it saw prescription growth across approved indications in areas of rheumatology, dermatology, and gastroenterology.

So, it's fair to say these two drugs could be on their way to compensating for the Humira loss -- and even driving additional growth.

Treating bipolar disorder and migraine

Meanwhile, AbbVie's neuroscience drugs, Vraylar for bipolar disorder and Botox treatment for migraine, also are proving to be significant growth drivers -- and AbbVie expects this to continue.

In the quarter, Botox sales rose 7%, and Vraylar sales climbed 35%. Regulators last year OKed Vraylar for use as an additional treatment for major depressive disorder, and since, AbbVie has seen solid gains in prescription growth. Both neuroscience drugs are blockbusters, generating billion-dollar annual revenue for the company.

Of course, declines in Humira are weighing on AbbVie, but this was expected, and the company prepared by renewing its portfolio. Importantly, the efforts are working. All of this is good news, even if earnings won't take off overnight.

Now let's consider the dividend. AbbVie launched back in 2013 as a spinoff of Abbott Laboratories, and since that time, it's lifted its quarterly dividend by 285%.

In the most recent quarter, it increased its payment by nearly 5% and emphasized its commitment to growing the dividend, modestly during times when earnings aren't growing, then more aggressively when earnings pick up. Over time, "we want to deliver a healthy, sustainable, growing dividend," chief operating officer Rob Michael said during the earnings call.

Is the stock a buy?

Let's get back to our question: Should you still buy this dividend stock? My answer is a big yes. AbbVie has the product portfolio necessary to spur another era of earnings growth, and we know this because these products are already starting to deliver on their promises. At the same time, the company is growing its dividend at a reasonable pace and making rewards to shareholders a priority.

Humira sales, as expected, are declining, but they aren't disastrous either. So, we can expect this blockbuster to continue offering some support to the top line.

Today, trading at about 12 times forward earnings estimates, AbbVie looks like a bargain, considering its management of the Humira situation, progress on newer drugs, and commitment to dividend growth. And that's why this pharmaceutical stock makes an excelling long-term buy right now.