Loughlan arrived at Portman Road alongside former manager Roy Keane in April 2009 while McParland was recruited seven months later.
"I have greatly enjoyed my time at Ipswich Town," McParland, nicknamed Charlie, told the club website.
"I wish the club and their new manager all the best for the future."
McParland took caretaker charge of two games after Keane's sacking last week.
He recovered from Sunday's 7-0 thrashing by Chelsea in the FA Cup to record a memorable 1-0 victory over Arsenal in the first leg of their League Cup semi-final at Portman Road on Wednesday.
You have to ponder if the colossal performance on Wednesday was down to them [McParland and Loughlan], what were they doing for the past year and a half?
JonahJameson
Town chief executive Simon Clegg added: "I'd like to thank Tony and Charlie for their commitment to Ipswich Town during their time at the club and wish them every success for the future."
McCarthy, who managed Southern Premier Division side Truro for 19 months, has signed a deal with Town until 2013.
He played alongside Jewell at Bradford, where he scored 60 goals in 131 games, and also featured for Swansea, Plymouth, Oldham and Exeter.
Source: BBC Sport
Source: BBC Sport