To prevent drawers being pulled out accidentally, fit a block of wood to the back of the drawer so that it catches on the front inside edge of the drawer unit to hold the drawer in place. Remove the drawer and fix the block with a screw, so that the block can pivot to reach approximately 12 mm above the top of the drawer.
Pivot the block upright and fit a second screw in position. Then remove the second screw, pivot the block down and slide the drawer back into position. Once the drawer is in place, turn the block upright again and reinsert the screw in the block.