Not having much detail to go by, it's difficult to answer the question directly as each situation is quite unique. Having said that, I do have some generic suggestions for you.

First of all, let your brother know how you feel about his constant requests for money in a non-argumentative way. When you do this, make sure that he doesn't feel ddefensive by assuring him that while you want to help him, you simply cannot keep lending him money for the sake of your (or your family's) solvency. Keep the conversation open enough that you may be able to get to the heart of the reason why he is always asking you for a handout.

If he is employed, perhaps he isn't making enough at his current job and should find a second job to supplement his income or look for other job opportunities that may or may not involve the need for further education.

If he's making enough and it's simply a matter of money mis-management, then try to connect him with a financial advisor who can help analyze his spending habits and set a budget. Advisors can also help educate him about making wise choices with money matters.

If he's resistant, suggest that you'll help him to find and advisor and even go with him to the initial meeting. This way, he'll see that you are still helpful and supportive of him even if you refuse to lend him any more money.

good points, thanks

Your brother will never stop as long as you keep giving in to him. Unless there are mitigating circumstances, you will have to cut him off and not feel guilty about it.