* Q1 adj. earnings of $2.46/share vs est of $2.83/share
* Raises fiscal 2018 earnings forecast to $11.80-$12.50/share
* Says comfortable with fiscal 2018 forecast
* Shares down 2.3 pct (Adds conference call details, shares)
July 27 (Reuters) - McKesson Corp, the biggest U.S. drug distributor, posted a much lower-than-expected quarterly profit, hurt by the lingering effects of a slowdown in the pace of price increases for branded drugs, sending its shares down as much as 6 percent.
The pharmaceutical supply chain, including pharmacy benefit managers and drug distributors, has been under pressure due to intense scrutiny over soaring drug prices.
McKesson said on Thursday its results were also hurt by the lapping effect of increased price competition in its independent pharmacy business.
Last year, the company raised concerns about aggressive pricing tactics from competitors and moderating pace of branded drug price increases as it slashed its fiscal-year earnings forecast.
"We entered this year with an assumption of branded inflation in the mid-single digits, and our first quarter experience was slightly ahead of this assumption," McKesson Chief Executive John Hammergren said.
Leerink analyst David Larsen said it appears that McKesson is not extracting as much value from the price-hikes as it would have in the past.
Larsen added that performance at the company's distribution business was a significant negative surprise, given a stabilizing environment in independent pharmacy networks and improving sentiment around pricing.
Net income attributable to McKesson fell 43 percent to $309 million, or $1.45 per share, in the first quarter ended June 30.
Excluding items, the company earned $2.46 cents per share, well below analysts' average estimate of $2.83, according to Thomson Reuters I/B/E/S.
Revenue rose nearly 3 percent to $51.05 billion, missing analysts' average estimate of $51.23 billion.
The company, however, raised its adjusted earnings forecast for fiscal 2018 to between $11.80 and $12.50 per share, up from $11.75 and $12.45.
The raised forecast implies that the company results will be more heavily weighted to second half of the fiscal year.
Evercore ISI analysts said some investors will question the steepness of the increase in the forecast, but expected share reaction to be modestly negative.
The company's results come a day after its shareholders voted against its executive pay policy, and said its compensation committee would conduct a thorough review of the policy.
The rebuke from McKesson's shareholders followed a campaign that criticized the drug wholesaler for its role in the U.S. opioid drug epidemic.
The company's shares pared early losses to trade down 2.5 percent at $162.20. Rivals AmerisourceBergen Corp and Cardinal Health Inc were both down about 1 percent. (Reporting by Ankur Banerjee and Anuron Kumar Mitra in Bengaluru; Editing by Saumyadeb Chakrabarty, Amrutha Gayathri and Martina D'Couto and Saumyadeb Chakrabarty)