<unk>  is a pain medication of the opiate family that is found naturally in a dark brown, resinous form, from the poppy plant (Papaver somniferum). It can be taken orally, sublingually, via inhalation, the trans-dermal route, inter-anally as well as via injection (both subcutaneously as well as<unk> re commonly intravenously. It acts directly on the central nervous system (CNS) to induce analgesia and alter perception and emotional response to pain. Physical and psychological dependence and tolerance may develop with repeated administration. It can be taken for both acute pain and chronic pain and is frequently used for pain from myocardial infarction, kidney stones, and during labor.<unk>  can be administered by<unk> uth, by injection into a<unk> scle, by injection under the skin, intravenously, injection into the space around the spinal cord, or rectally. Its maximum effect is reached after about 20 minutes when administered intravenously and 60 minutes when administered by<unk> uth, while the duration of its effect is 3–7 hours. Long-acting formulations of<unk>  are available as<unk> -Contin, Kadian, and other brand names as well as generically. Potentially serious side effects of<unk>  include decreased respiratory effort, vomiting, nausea, and low blood pressure.<unk>  is addictive and prone to abuse. If one's dose is reduced after long-term use, opioid withdrawal symptoms may occur. Common side effects of<unk>  include drowsiness, vomiting, and constipation. Caution is advised for use of<unk>  during pregnancy or breast feeding, as it may affect the health of the baby.<unk>  was first isolated between 1803 and 1805 by German pharmacist Friedrich Sertürner. This is generally believed to be the first isolation of an active ingredient from a plant. Merck began marketing it commercially in 1827.<unk>  was<unk> re widely used after the invention of the hypodermic syringe in 18531855. Sertürner originally named the substance<unk> rphium, after the Greek god of dreams,<unk> rpheus, as it has a tendency to cause sleep. The primary source of<unk>  is isolation from poppy straw of the opium poppy. In 2013, approximately 523 tons of<unk>  were produced. Approximately 45 tons were used directly for pain, an increase over 400% the last twenty years.<unk> st use for this purpose was in the developed world. About 70 percent of<unk>  is used to make other opioids such as hydromorphone, oxymorphone, and heroin. It is a Schedule II drug in the United States, Class A in the United Kingdom, and Schedule I in Canada. It is on the World Health Organization's List of Essential Medicines.<unk>  is sold under many trade names. In 2019, it was the 163rd<unk> st commonly prescribed medication in the United States, with<unk> re than 3million prescriptions.
Morphine
Codeine
Nalorphine
Methadone
Isomethadone
Normethadone
Butorphanol
Fentanyl