The pharmaceutical industry is a natural hunting ground for reliable income stocks, since people buy drugs in good times and in bad. But which high-yield dividend stocks are actually worthy of your investment dollars? We posed that question to a team of Motley Fool healthcare investors, and they picked Pfizer (NYSE:PFE),  GlaxoSmithKline (NYSE:GSK), and Novo Nordisk (NYSE:NVO).

Dollar signs in drug packets being manufactured

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A dividend stock with staying power

George Budwell (Pfizer): With a yield of 3.92% at present, Pfizer offers one of the richer dividends among its big pharma peer group. But the real reason to buy this dividend stock is arguably for its staying power.

Unlike many of its closest peers, Pfizer hasn't tied itself to a single flagship drug or drug candidate as its main growth driver throughout the course of its history. Instead, this pharma titan has built a diverse portfolio of medicines that has, so far, been able to withstand the loss of exclusivity for several megablockbuster medicines in the recent past. And that's a key reason why this drugmaker is clearly one of the safer bets in the realm of dividend-paying pharma stocks. 

Turning to the details, Pfizer has recently emerged as a leader in the high-growth oncology space by bringing the novel breast cancer drug Ibrance to market, and subsequently acquiring the advanced prostate cancer treatment Xtandi last year. Not long after, the drugmaker also grabbed its first regulatory approval for its joint-owned cancer immunotherapy Bavencio as a treatment for metastatic Merkel cell carcinoma. And just last week, the company struck gold again in oncology with the Food and Drug Administration (FDA) approval of its leukemia medicine Besponsa.   

Although Pfizer's top-line growth may not be overly impressive at the moment thanks to the ravages of the patent cliff -- 2.6% projected revenue growth for 2018 -- the company's "strength-in-numbers" strategy has at least kept it heading in the right direction during this difficult period. While the drugmaker's 12-month, trailing payout ratio of 90.5% may raise some eyebrows among income investors, the company's diverse product portfolio and stellar clinical pipeline are arguably two compelling reasons to think that a dividend reduction simply isn't a major risk factor at this stage. 

This 5% Big Pharma yield is worth a look 

Sean Williams (GlaxoSmithKline): Pharmaceutical stocks are known for their strong pricing power, healthy profits, and above-average dividend yields. But among the roughly one dozen large pharmaceutical stocks that are affably referred to as big pharma, it's the U.K.-based GlaxoSmithKline, with its 5.1% yield, which stands out.

You could say things were a bit hairy for GlaxoSmithKline just a few years prior, with sales of its top-selling asthma and COPD drug Advair slowing and preparing for the entrance of generic competition. At the same time, next-generation COPD and asthma therapies that hit the market and were designed to replace lost Advair sales were slow to grow due to a lack of adequate insurance coverage and the need to unseat mature drugs that had been go-to therapies for years.

The good news for shareholders and GSK is that both its respiratory and infectious-disease portfolios are now firing on all cylinders, even as sales of Advair continue to decline. In fact, growth from new products is outpacing the loss in sales from mature products facing generic threats.

Respiratory sales in the recently finished second quarter wound up totaling $2.33 billion, an increase of 4% on a constant-currency basis, led by triple-digit percentage sales growth in Nucala and Arnuity Ellipta, as well as constant-currency sales growth of 67% in Anoro Ellipta, and 75% in Breo Ellipta. Breo's $364 million in Q2 sales put it on track for possibly $1.5 billion in full-year sales.

Vaccines have also been a major part of Glaxo's success. A three-part asset swap with Novartis in 2015 gave Glaxo a healthier balance sheet -- it netted quite a bit of cash in the process -- and a more robust vaccines portfolio, which should boost its pricing power over time. Novartis didn't do too shabby, either, picking up Glaxo's oncology assets in the process.

In the most recent quarter, GlaxoSmithKline wound up reporting strong growth in both blockbuster HIV meds Tivicay and Triumeq of 37% and 44%, respectively, on a constant-currency basis. Since there's no effective cure for HIV, these are two therapies that could remain foundational for years to come.

Long story short, GlaxoSmithKline is over its patent-cliff hump and its pipeline is once again a promising catalyst, not a drag on its valuation. High-yield income seekers would be wise to give this Big Pharma a closer look.

The top-dog in diabetes

Brian Feroldi (Novo Nordisk): Diabetes is a multi-billion dollar indication that, sadly, is poised for significant growth in the decades ahead. Danish pharma giant Novo Nordisk has been a major player in this disease for decades, and its long-term investors have been treated extremely well.

However, 2016 proved to be a rough year for shareholders. Increased competition from the likes of Eli Lilly and Sanofi allowed insurers to put huge pricing pressure on Novo's legacy insulin products. In turn, Novo's margins dipped, and management was forced to cut its long-term profit growth guidance in half. Wall Street didn't take the news well.

Thankfully, Novo's recent results show that the company is on the upswing, once again. Revenue and earnings are on the rise, thanks to strong sales growth of its GLP-1 drug Victoza. At the same time, fast sales growth of its next-generation insulins -- which includes Tresiba, Xultophy, and Ryzodeg -- are almost fully offsetting the weakness in its legacy insulin products.

Looking down the road, Novo has a number of products in its pipeline that promise to reignite growth. This includes a GLP-1 drug with a weekly dosing schedule, an ultra-fast rapid-acting mealtime insulin, next-generation hemophilia drugs, and more.

Between its current product portfolio and pipeline, Novo's profits are expected to grow around 8% annually over the next five years. That's not too shabby for a company that's trading at a below-market multiple. Throw in a dividend yield of 2.45% that only consumes half of its earnings, and Novo Nordisk is a big pharma worth checking out.

Brian Feroldi has no position in any stocks mentioned. George Budwell owns shares of Pfizer. Sean Williams has no position in any stocks mentioned. The Motley Fool recommends Novo Nordisk. The Motley Fool has a disclosure policy.