Merck (MRK 0.95%) topped analysts' consensus earnings estimates every time the company reported quarterly results in 2018. That's one of the reasons why Merck's share price soared nearly 36% last year.

The big drugmaker announced its 2018 fourth-quarter results on Friday, Feb. 1, 2019, before the market opened. Was Merck able to keep its streak of earnings beats going? Were there any surprises? Here are four things you need to know about Merck's Q4 results. 

Three scientists in a lab

Image source: Getty Images.

1. Another quarter, another beat

Yes, Merck yet again made Wall Street happy. The company reported Q4 revenue of $11 billion. Analysts expected $10.94 billion. Merck posted adjusted earnings per share (EPS) of $1.04, narrowly beating the consensus estimate of $1.03.

The drugmaker's revenue would have looked even better were it not for currency fluctuations. Merck stated that the negative impact on its top line from foreign exchange lowered year-over-year growth by around 3%. With this impact included, revenue in the fourth quarter increased by 5% over the prior-year period. Merck's adjusted EPS grew 6% year over year.

2. Keytruda continued to be unstoppable

If Merck were a football team, Keytruda would be the star running back. And probably quarterback, tight end, and wide receiver, too. The cancer drug's momentum continued to be unstoppable.

Merck reported Q4 sales for Keytruda of nearly $2.2 billion -- nearly one-fifth of the company's total revenue. This sales figure reflected a whopping 66% year-over-year increase. The company said that Keytruda enjoyed strong momentum in the non-small cell lung cancer (NSCLC) indication and picked up even more steam from launches in new indications in multiple countries.

3. The "solid six" delivered double-digit growth

As successful as Keytruda was for Merck in the fourth quarter, it wasn't the company's only star performer. Merck claimed six other top product lines that delivered solid double-digit growth in Q4.

The biggest winner among the group was Gardasil, with sales for the HPV vaccine soaring 32% year over year to $835 million. Sales for Bridion, an injection for reversing neuromuscular blockade induced by rocuronium bromide or vecuronium bromide in adults undergoing surgery, increased 23% over the prior-year period to $256 million. Sales for pneumococcal vaccine Pneumovax 23 rose 22% year over year to $322 million.

Merck's measles, mumps, rubella, and varicella vaccine franchise, which includes ProQuad, M-M-R II, and VariVax, saw Q4 sales increase by 13% to $455 million. Sales for birth control device NuvaRing jumped 15% to $216 million. And revenue from the company's companion animals products grew 12% year over year to $352 million.

4. Big problems still the big problems

Despite plenty of bright spots for Merck in the fourth quarter, there are were also challenging areas. And the drugmaker's big problems of the past were still its big problems in Q4.

Merck faced stiff headwinds for a laundry list of drugs for which sales are slipping due to either loss of exclusivity or significant challenges from newer and more effective products. This list includes diabetes drugs Januvia and Janumet, cholesterol drugs Zetia and Vytorin, hepatitis C virus drug Zepatier, HIV drug Isentress, immunology drug Remicade, anti-infection injection Invanz, and shingles vaccine Zostavax.

Check out he latest Merck earnings call transcript.

Looking ahead

Merck expects full-year 2019 revenue between $43.2 billion and $44.7 billion. The midpoint of this range reflects growth of around 4% compared to 2018. The company also projects adjusted EPS for 2019 between $4.57 and $4.72. The midpoint of this range represents a year-over-year increase of around 7%.

This guidance wasn't horrible. But single-digit growth on the top and bottom lines probably won't be enough for the company to rank as one of the top stocks of the Dow Jones in 2019, as it did in 2018.