Not really. 'Meanwhile' means at the same time. For example: 'John waited for the baggage to arrive. Meanwhile, Mary went to pick up the hire car'. This suggests that both actions happened simultaneously. 'In the meantime' refers to a temporary situation , usually when you are waiting for something to happen. For example: 'Your computer won't be fixed until the end of the week. In the meantime, you can borrow someone's laptop.'

UPDATE: Su.Ki. is correct (of course). “meanwhile” has two different meanings: 1) (which is synonymous with “in the meantime”) In the intervening period of time: ‘meanwhile, I will give you a prescription for some pills’ 2) (which is not the same as “in the meantime”): At the same time: ‘steam for a further five minutes; meanwhile, make a white sauce’ Can we agree on this Su.Ki.?