Growth stocks often don't come cheap, especially when their prospects look great, as is the case with Eli Lilly (LLY 1.09%). It is the most valuable healthcare company in the world, with a market cap of around $800 billion. And yet it may still not be too late to invest in it.

The company's dominance in the GLP-1 drug market makes it a promising long-term investment to hang on to. Last year, its sales rose by 32%, but there could be even more growth on the horizon.

Eli Lilly is going after compounding pharmacies

Pharmaceutical giant Eli Lilly has been experiencing a surge in revenue growth lately due to the massive popularity of its two GLP-1 drugs, Zepbound and Mounjaro. The former is approved for weight loss and the latter for diabetes. They can help patients shed significant pounds and transform their lives for the better. Demand has been through the roof, and they generated a combined $16.5 billion in sales last year.

But there's been one problem: Compounding pharmacies have been offering knock-off versions of these drugs due to shortages. Those shortages are now over, but compounding pharmacies are still offering these drugs. Eli Lilly is now suing these companies in an effort for them to stop.

Not only could compounded versions divert sales away from Eli Lilly to other companies, but if there are any side effects related to these products, patients may have a negative perception of the drugs, perhaps not realizing that they aren't exact copies of the approved GLP-1 treatments. Thus, there are multiple reasons for Eli Lilly to stop sites from offering compounded versions of its GLP-1 drugs. They could not only help sales, but they can also help protect its brands.

The company may have more catalysts ahead

Eli Lilly isn't done in developing new weight loss treatments. In fact, the best may still be to come, as it's working on a pill, which could be a game changer for the industry. Currently, its GLP-1 treatments are injectables, which may not be that appealing to some patients. An effective weight loss pill, however, may be a much more attractive option to a wider section of the population.

In April, the company reported that a late-stage trial of orforglipron, its daily weight loss pill, showed that the drug could help people lose weight and reduce their blood sugar levels. That's great news for the company, and it gave the stock a boost.

But there is still much more trial data to come this year. In June, data is expected to come out looking at the long-term safety of the drug, and how well it worked with Metformin. There are a total of nine studies that Eli Lilly plans to complete this year relating to how orforglipron performs as a weight loss and diabetes treatment, with the last release slated for October.

Approval for orforglipron could come next year, but how it does in these trials will give investors a good idea whether that approval is likely. And if those prospects are strong, it wouldn't be surprising to see the healthcare stock take off on the developments.

Eli Lilly stock could prove to be a no-brainer buy right now

It has been a strong start to the year for Eli Lilly on news of its recent trial data on orforglipron. But there could be more gains to come for investors who buy the healthcare stock today. It isn't a cheap buy, trading at more than 70 times its trailing earnings, but given just how much growth is ahead for the business, especially if it obtains approval for a weight loss and diabetes pill, it can still be a no-brainer buy at these levels.