Pharmacology Study Set 3

Nursing

Quiz 12 :
Sedative-Hypnotic Drugs and Alcohol

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Quiz 12 :
Sedative-Hypnotic Drugs and Alcohol

For maintaining sleep sedative-hypnotic drugs can be used often, but it may lead to alteration of a normal sleep cycle. There are two phases for normal sleep and they are Rapid Eye Movement (REM) Sleep and Non-Rapid Eye Movement (NREM) Sleep. Sleep cycle can thus be otherwise called a REM-NREM cycle. Sedatives are drugs which are used mainly for reducing anxiety and excitement and to make a patient calm. If given in high dosage, a sedative may cause sleep. It controls the mental function from the limbic system and these are usually very slow to act. Drugs which helps in getting sleep is called hypnotics and they have very sudden action. Hypnotics in heavy doses may produce general anaesthesia. It controls this function through midbrain. The difference between both sedatives and drugs is that even if both of them are same drugs used in different doses, if the dosage is low, it can be called as a sedative and if the dosage is high, it can be called a hypnotic.

For maintaining sleep sedative-hypnotic drugs can be used often, but it may lead to alteration of a normal sleep cycle. There are two phases for normal sleep and they are Rapid Eye Movement (REM) Sleep and Non-Rapid Eye Movement (NREM) Sleep. Sleep cycle can thus be otherwise called a REM-NREM cycle. Drugs which helps in getting sleep is called hypnotics and they have very sudden action. Hypnotics in heavy doses may produce general anaesthesia. It controls this function through midbrain. The difference between both sedatives and drugs is that even if both of them are same drugs used in different doses, if the dosage is low, it can be called as a sedative and if the dosage is high, it can be called a hypnotic. Hypnotic drugs may create a loss of memory and confusion. Hence, a proper record should be maintained about the time of medication in order to avoid overdose of these drugs.

Barbiturates are the oldest sedative-hypnotic drugs having their structure similar to the parent compound called barbituric acid. These drugs produce the CNS depression depending on their dose and at higher doses, these drugs cause general anesthesia. The mechanism of action of these drugs includes the binding to the GABA-receptor mediated chloride channel drug receptors and increasing the chloride influx resulting in the nerve membranes hyperpolarization. These inhibitory actions also reduce the reticular activating system (RAS) activity and depending on dose, increase the sleep or sedation. Barbiturates usually increase the sleep of stage 2 when used as hypnotic and decrease the slow-wave sleep besides suppressing the REM sleep. When these drugs are stopped, the REM rebound is seen in which excess REM sleep time is spent by the patient for next day or two to make up the REM sleep loss. At this time, there is increase dreaming leading to the restlessness, nightmares and anxiety. Benzodiazepines are also known as antianxiety drugs as these are used in the anxiety treatment. Besides, antianxiety effects, these drugs were also used as muscle relaxant, anticonvulsant, sedative hypnotics. The mechanism of action of these drugs includes increasing the gamma-aminobutyric acid (GABA) inhibitory activity and these drugs also bind to the receptor sites which are close to the GABA receptors. The GABA action the benzodiazepine drug action increase the chloride channel opening frequency leading to the nerve membrane hyperpolarization decreased activity of neurons. This depression produce in the RAS, based on the dose, the sedation or hypnosis. The effects of benzodiazepines on sleep cycle is to increase the NREM stage 2 and decrease the NREM stage 4. However, these drugs do not suppress the REM sleep and hence when these drugs are stopped, there is no REM rebound. Hence, the options (B), (C), (D) and (E) are incorrect. Both barbiturates and benzodiazepines increase the stage 2 NREM sleep. Hence, the option img is correct.

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