mephobarbital: a long-acting crystalline barbiturate (trade name Mebaral) used as a sedative and as an anticonvulsant in the treatment of epilepsy
anticonvulsant: a drug used to treat or prevent convulsions (as in epilepsy)
ripcord: a cord that is pulled to open the gasbag of a balloon wide enough to release gas and so causes the balloon to descend