As with most things in life, there are no guarantees in investing. Some investments pan out and some simply don't. One way to grow wealth that has a great track record of working is to pick proven businesses that will almost certainly be around in 10, 20, or 30 years, invest in them, and then be patient.

Here are two drugmakers with decades of successful operations that demonstrate their ability to produce year in and year out. Either has what it takes to create wealth for shareholders over the long run.

A doctor and patient talk during an appointment.

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1. Johnson & Johnson: The largest pharmaceutical company on the planet

Tracing its history back to 1886, Johnson & Johnson (JNJ 0.59%) is among the oldest healthcare companies in the U.S. It shouldn't come as a shock to also learn that J&J's $427 billion market capitalization also makes it the biggest drugmaker in the world.

The company's portfolio of pharmaceuticals is led by its immunology drug Stelara and its cancer treatment Darzalex. Both were megablockbusters (with $5 billion or more in annual sales) in 2022. J&J's portfolio also contained a blockbuster (at least $1 billion in annual sales) COVID-19 vaccine and 12 blockbuster drugs, including the antipsychotic medicine Invega and the blood thinner Xarelto.

It's drug portfolio demonstrated strong past performance, and the company's future appears to be just as promising. As of Jan. 24, J&J has roughly 110 indications in differing stages of clinical development. Several of these drugs could end up becoming blockbusters, such as the blood-thinner drug candidate milvexian, created through a partnership with Bristol Myers Squibb. This is why the average analyst estimate of 4% annual earnings growth over the next five years could prove to be on the conservative side.

Income investors will appreciate J&J's 2.8% dividend yield, which is significantly higher than the average 1.7% yield of the S&P 500 index. With its dividend payout ratio set to come in at around 45% for 2023, investors can be confident that J&J's dividend is quite safe with room for increases. The cherry on top is that shares of the company can be picked up at a forward price-to-earnings (P/E) ratio of 15.6, which is in line with the sector average.

2. Novartis: A reliable pick for income investors

Swiss pharmaceutical giant Novartis (NVS 1.23%) is a conglomeration of multiple drugmakers, some of whom had operations dating back to the 1850s. That makes it one of the oldest drugmakers in the world. As you'd expect for such a well-established company, this company is huge: Its $217 billion market cap positions it as the seventh-largest in the world.

Headed by the immunology drug Cosentyx and the heart-failure drug Entresto, Novartis' product portfolio consisted of 14 blockbuster medicines in 2022. Adjusting for unfavorable foreign currency translations stemming from the strong U.S. dollar, 10 of these 14 drugs grew net sales during the year.

Novartis' existing portfolio of medicines is its strength. And with 150-plus indications currently in clinical development in its pipeline, the company also should have a solid future. That's why analysts believe that Novartis' earnings will compound by 6.9% annually over the next five years.

Investors don't have to sacrifice income for these decent growth prospects, either: The stock's 3.6% dividend yield is more than double that of the S&P 500 average. And with its dividend payout ratio expected to come in at just above 49% for 2023, Novartis' dividend is well-covered.

Yield-focused investors can pick up shares of the stock at a forward P/E of 13.6, a discount to the sector average. That arguably makes Novartis a buy for income investors.