Option traders' accounts were injected with major gains in a bevy of pharmaceutical companies on Tuesday, via bullish positions opened within a three-day period of each other ahead of the earnings cycle.

-In Merck & Co. Inc.  (MRK) , on July 10, Investitute's tracking systems detected the purchase of 10,000 August $65 calls, expiring on August 17, for $0.55 to $0.64 with shares at $62.51. Volume was above the strike's open interest of 9,026 contracts, indicating that this was fresh buying. Investitute co-founder Jon Najarian cited the unusual activity at that time on CNBC's "Halftime Report."

-In Pfizer Inc.  (PFE) , on July 11, Investitute's market scanners found that 1,300 Weekly $37.50 calls expiring on August 24 were purchased for $0.51 to $0.53 as part of a bullish roll with shares at $37.20. Open interest in the strike was only 122 contracts before the trade occurred, showing that this was a new position.

-Lastly in Eli Lilly & Co.  (LLY) , on July 13, Investitute's market scanners identified the purchase of 2,000 August $90 calls, expiring on August 17, for $1.41 to $1.47 with shares at $89.05. Volume was well above the strike's open interest of 1,133 contracts, showing that this was fresh buying.

These investors may have been betting that the 'drug pricing war' was a non-event and that the upcoming earnings cycle would show continued growth and profitability in the healthcare sector, notably, the big pharma names like MRK, PFE, and LLY.

-Those MRK August $65 calls traded up to $1.60, nearly three times their initial purchase price. The stock rose 5.76% in the same period after it beat earnings and revenue estimates before the market opened on Friday, July 27.

-Those PFE 24August $37.50 calls traded as high as $2.47, more than 4.5 times their purchase prices. The stock rose 7.47% in the same period, and closed on Tuesday up 3.47% to $39.93, just off an all-time high of $39.99 printed earlier in the session. The drug and health-care products company beat quarterly estimates on the top and bottom lines Tuesday morning.

-Lastly, those LLY August $90 calls sold for as much as $9.08, more than six times their purchase prices. The stock rose 11.14% in the same time frame, and LLY was up 0.79% to $98.79 Tuesday. The pharmaceutical has been rallying since reporting strong quarterly results on July 24.

Long calls lock in the price where investors can buy a stock, letting them position for a rally at limited cost with the potential for significant leverage. They carry less risk than owning shares because the most that can be lost is the price of the options no matter how far the stock might fall.