Take a nap. If you can't stop for the night, at least pull off at a safe place, such as a rest area or truck stop, and take a nap. There are no drugs that can overcome being tired. While they may keep you awake for a while, they won't make you alert. And eventually, you'll be even more tired than if you hadn't taken them at all.
Sleep is the only thing that can overcome fatigue.
People who drink alcohol are involved in traffic accidents resulting in over 20,000 deaths every year. How it affects driving. Laws regarding drinking and driving. Legal, financial, and safety risks of drinking and driving. The Truth About Alcohol.