Propranolol (Inderal)
Propranolol is one of a class of medications called beta blockers it had formerly been very heavily prescribed for high blood pressure. However, by blocking the adrenalin receptor site in the muscle, Propranolol also blocks the so-called "fight-or-flight" response, and can thereby help maintain calmness in tense and nervous social situations. Recommended for performance anxiety situations, stage fright, etc. Use of beta-blockers has been banned in professional snooker tournaments.

Dosage: 10mg-20mg with some food two hours before the time needed. Frequently a dose as low as 5mg can take the nervous edge away.
Precautions : Propranolol lowers the blood pressure, and therefore should not be used by people with very low blood pressure.People on any other medications or with arterial problems, or bronchial problems, asthma, etc. should check with their physician before usage. Propranolol should be taken with food to avoid  nausea.