Shares of Eli Lilly and Company (LLY -2.02%) have soared nearly 35% so far in 2024 and are only a few points away from doubling over the last 12 months. The company reigns as the biggest drugmaker in the world based on market cap. It's also the largest company in the entire healthcare sector.

But has Lilly peaked? I don't think so. Here's why Lilly stock remains a screaming buy.

1. Tremendous growth ahead for Mounjaro and Zepbound

The expression "selling like hotcakes" might need to be changed to "selling like Mounjaro and Zepbound." Lilly can't make enough of its type 2 diabetes and weight loss drugs to keep up with demand -- and that's after significantly ramping up its production capacity.

In the first quarter of 2024, the two products (which are the same drug, tirzepatide, sold under different labels) generated sales of over $2.3 billion. Zepbound is now beating Novo Nordisk's Wegovy, capturing nearly 57% of new-to-brand prescriptions at the end of Q1.

This is only the beginning. Lilly CEO Dave Ricks said in the Q1 earnings call that Zepbound had access to 67% of the U.S. commercial market as of April 1, 2024. Medicare will only pay for obesity drugs that are approved for other indications. Lilly plans to file for regulatory approvals this year for tirzepatide in treating obstructive sleep apnea, which should open up the big Medicare market.

More additional indications for tirzepatide could also be on the way. Lilly expects to file for U.S. approval of the drug in treating heart failure with preserved ejection fraction (HFpEF) later this year. It's also evaluating tirzepatide in a phase 2 study targeting metabolic-associated steatohepatitis (MASH), which is also known as nonalcoholic steatohepatitis (NASH). Some analysts think the NASH/MASH market presents a $100 billion-plus annual opportunity.

2. Potentially better weight-loss drugs in the pipeline

As good as Mounjaro and Zepbound are, Lilly could have even better weight-loss drugs in its pipeline. The company is evaluating orforliprin (a once-daily oral therapy) and retatrutide in late-stage testing, and bimagrumab and mazdutide are in phase 2 studies. Lilly has DACRA QW II in phase 1 testing.

Chief Scientific Officer Dan Skovronksy said in the Q1 call that the company is "excited about the portfolio of earlier-stage obesity molecules." He thinks these programs have the potential to improve upon tirzepatide by increasing the quality of weight loss, reducing side effects, and requiring less frequent administration.

3. Many more promising candidates

Lilly's obesity programs alone will be major growth drivers for a long time to come. However, the company has many more promising candidates in the hopper. Two of them -- donanemab and mirikuzumab -- already await regulatory approval.

The U.S. Food and Drug Administration (FDA) plans to convene an advisory committee to review the submission for donanemab in treating early-stage Alzheimer's disease. Anne White, president of Lilly Neuroscience, said in the Q1 call the company remains "incredibly confident" in the potential for the drug. She noted that Lilly isn't sitting still while it waits for the advisory committee and is doing all it can to ensure a successful launch, pending approval.

Lilly filed for approval in the U.S. and European Union for mirikizumab in treating Crohn's disease. It also resubmitted for FDA approval of the drug in treating atopic dermatitis following a complete response letter from the agency due to issues with a third-party manufacturer.

But what about valuation?

The main criticism some investors will have about Lilly is its valuation. The drugmaker's shares trade at a forward price-to-earnings (P/E) ratio of 62.5. That's seemingly at a nosebleed level.

However, forward P/E multiples only look one year into the future. Lilly should deliver significant growth through the rest of the decade and beyond.

No, the stock isn't cheap. But valuation isn't a major concern, in my view, considering Lilly's tremendous growth prospects.