A substance with sedative effect comprises a therapeutically effective amount of a gamma-pyrone such as comenic acid in a pharmaceutically acceptable carrier. When administered at a daily dosage of between 0.05 mg to about 10,000 mg of active ingredient per unit dose, the substance can be used to treat various disorders of a nervous system such as pain, insomnia, anxiety, neurosis, depression, as well as withdrawal symptoms experienced by drug addiction patients, especially for patients addicted to opiate-based drugs. The substance can be delivered in a number of ways of systemic administration of a pharmaceutical agent including oral, parenteral, transdermal, and transmucosal administration. One disclosed method of administration involves a subcutaneous implant providing a continuous release of an active ingredient at an effective daily rate over the entire treatment period ranging from 5 to 30 days, and preferably from 13 to 20 days.