Sedatives have been used by doctors and individuals in many ways over the years. From medical uses to the entertainment industry, and even street drugs, sedatives have played a significant role in our society for a long time. Popularized in films and popular television shows, sedatives can be found almost anywhere. From the highly addictive prescription sleep aids to the very safe and often lifesaving recreational drugs, sedatives are used in a wide variety of situations and for a wide range of reasons. Today, most people don’t think twice about the possibility of taking a sedative to calm a hyperactive child or to help someone overcome anxiety (1).
Sedatives have evolved over the years to become much more widely available and can be bought over-the-counter. While commonly used for routine administration of a wide range of medications, sedatives are particularly popular in the field of medicine. While some of the drugs have serious side effects, many provide a comfortable, peaceful environment in which to take the prescribed dosage and provide a measure of relief from the effects of a critical illness or injury. Sedatives have also proven effective in the treatment of acute injuries and serious illnesses and can even be administered to help chronic patients control their symptoms during times of disease or severe fatigue (2).
A Brief History of Sedatives.
Historically, sedatives have been used to treat a number of medical conditions, cancer, including their use as anesthesia for surgery, and even a type of stimulant called barbiturates. Popular sedatives that are most often taken for procedures in the ICU include midazolam, dipiazepines, and rocuronium. The history of sedatives goes back hundreds of years and can be traced to the ancient Egyptians who routinely administered a mixture of opium and barbiturates in the operating room to help alleviate pain and distress. Sedatives, which were also commonly used by the Chinese in the form of acupuncture needles, were first used in Europe in the 18th century as a method to induce sleep (2a).
Categories of Sedatives
Sedatives, which come in three classifications, fall into two main categories. The first, known as non-benzodine sedatives, act in a different way than most other sedatives and are classified according to how long they act. They fall into one of three forms: immediate, intermediate, and delayed. Immediate sedatives generally act in a more rapid onset and effect, often within a few minutes of ingesting the drug. These drugs work to reduce the perception of bodily discomfort and to create a very relaxing environment.
The second category, known as benzodiazepines or TCAs, acts more gradually and has a longer-lasting effect. These sedatives can be grouped according to how long they act and also according to how quickly they affect the blood-brain barrier. TCAs act at slower rates and may take as long as 30 minutes to affect the blood-brain barrier. While all three types share some similar symptoms including restlessness, anxiety, phobias, nightmares, irritability, tremors, hyperventilation, slurred speech, and muscle twitching, their methods of action and effects will differ greatly.
Barbiturates are common in the practice of dentistry and are usually used for patients with minor dental problems that cause them to wake frequently. Barbiturates, along with other sedatives, function by suppressing the voluntary nervous system and central processing centers of the brain. The sedatives work by blocking the transmitters that excite the nerves and transmit the information from them to the brain through the blood-brain barrier. Some barbiturates excite the respiratory tract by blocking the nerve impulses controlling breathing. Barbiturates have sedative properties that are almost identical to those of oxygen, but they are more highly concentrated and thus have a longer-lasting effect on the body. They are generally administered intravenously or orally, with liquids usually being the preferred method of administration.
Benzodiazepines are commonly used in the treatment of anxiety disorders and other psychiatric conditions with a long-term effect on the cardiovascular system. These drugs act rapidly by inducing a state of relaxation and calming the patient. They reduce the rapid onset of unconsciousness, respiratory depression, and unconsciousness following cardiac arrest. Some benzodiazepines such as alprazolam also cause a form of amnesia, which is typically temporary. There are many side effects of these drugs that should be considered when considering their use, especially when using them in combination with other medications such as nitrates.
While these three classes of sedatives are widely used, the slowest effect level is attained by continuous infusion of propofol. Continuous infusion of propofol results in a profound effect over a one to two-hour period, with the drug steadily draining into the bloodstream at a rate of approximately one liter per minute. Because the effects of propofol are often profound, patients are usually given this drug in a hospital setting under close medical supervision.