What is anterograde amnesia and drugs that may cause it?

Anterograde amnesia refers to the inability of a person to remember events that happened in the time that the drug was in its duration of action. Drugs that cause this are benzodiazepines, for example diazepam, midazolam, lorazepam, etc.

 

Effects of sedative-hypnotic drugs on normal sleeping pattern and the significance thereof.

Sedative-hypnotics drugs decrease the (latency of sleep onset) time to fall asleep and the patient suffering from insomnia or any sleeping disorder will be able to fall asleep faster if they make use of benzodiazepines or older sedative-hypnotics.

These drugs also increasing the total sleep duration (duration of stage 2 NREM is increased), if the patient is only used to receiving less than 6 hours of sleep per night. Therefore, if the patient struggles to sleep for more than 6 hours per night, the use of sedative-hypnotic drug will increase the total sleep duration.

Benzodiazepines decrease REM (Rapid Eye Movement) sleep if given in high doses. Thus, if the patient uses benzodiazepines, he/she may experience less dreaming, but also it affects the brain area responsible for learning and memory.

A decrease in stage 4 NREM (Non-Rapid Eye Movement) slow-wave sleep can be expected as a result of the use of sedative-hypnotics. During this stage the patient will be in a deep sleep and possibly dreaming. Using sedative-hypnotics will make it easier for the patient to wake up as the period of stage 4 NREM is shortened.

 

Sedative-hypnotic drugs that are used as a supplementary therapy in anesthesia and why?

Barbiturates, thiopental and methohexital are used solely as anesthesia because they are very lipophilic and are able to penetrate brain tissue and distribute rapidly after intravenous administration. However, benzodiazepines (like midazolam, diazepam and lorazepam) in high doses are used as supplementary agents as adjuncts to general anesthesia. They are used as supplementary agents because they have relatively long half-lives, form active metabolites and slow onset of action. This effect lasts long and persists to post anesthesia.

 

Sedative-hypnotic drugs are used as anticonvulsants?

Benzodiazepines, like diazepam, lorazepam. Are used to treat seizures and status epilepticus. They show selective anticonvulsive effects with phenobarbitone, clonazepam and clobazam. If barbiturates, phenobarbital and metharbital are given in high doses, they are effective to treat generalized tonic-clonic seizures and they produce anticonvulsive effects (although it is not a first line treatment).

 

What is the mechanism of the muscle-relaxing effects of the carbamates and the benzodiazepines?

These drugs exert an inhibitory effect on the polysynaptic reflexes and internuncial transmission. At high doses they depress transmission at the skeletal neuromuscular junction, which leads to muscle relaxation. In this way, muscles that are in spasms can also be relaxed after the use of carbamates and benzodiazepines.

 

Effects of the sedative-hypnotic drugs on the respiratory and cardiovascular systems.

At hypnotic doses in healthy patients, effects on respiration change during natural sleep. At therapeutic doses, respiratory depression is produced in patients that have pulmonary diseases. The effects thereof are dose-related and the depression of the medullary respiratory centre is usually the cause of death – due to overdosing.

Doses of sedative-hypnotics that cause hypnosis have no significant cardiovascular effects on healthy patients. Whereas, in patients with cardiovascular diseases and impairments, normal doses lead to cardiovascular depression, as a result of its action on the medullary vasomotor centre in the brain. At toxic doses0, circulatory collapse can be expected, as the drugs depress centrally and peripherally via facilitation of adenosine.

Cardiovascular and respiratory depression becomes more intensified when the sedative-hypnotic drugs are given intravenously.