What does anterograde amnesia mean and which drugs can cause this effect?

• Anterograde amnesia is an inability to remember events occurring during a drug’s duration of action. Drugs that can cause anterograde amnesia are Benzodiazepines.

Name the effects of the sedative-hypnotic drugs on the normal sleep pattern and explain their significance to the patient.

• The effects that sedative hypnotics has on sleep patterns are:
  • Decrease in the time it takes to fall asleep.
  • Increase in a patient’s total sleep duration, for patients who normally sleep less than  hours a night.
  • Benzodiazepines have a small decreasing effect of REM sleep (rapid eye movement), and higher doses of BD’s would decrease the REM sleep of a patient.
  • BD’s also increase the duration of phase 2 NREM sleep (non-rapid eye movement) of a patient and decreases the duration of phase 4 NREM sleep in a patient.
• The significance of these sedative hypnotics to the patient would mean that the patient would get an increase in their sleep if the patient struggles to sleep.

Which of the sedative-hypnotic drugs are used as a supplementary therapy in anaesthesia?  Can you explain why?

• Barbiturates like Thiopentone and BD’s like Midazolam, Diazepam and Lorazepam can be used as supplementary therapy in anaesthesia. Thiopentone can be used as supplementary because of the fact that it is a lipid soluble drug that can cause sedation and can be used as an induction anaesthetic.  The BD’s can be supplementary because they cause CNS suppression and can help patients to fall asleep during procedures.

Which of the sedative-hypnotic drugs are used as anticonvulsants?

• High dosages of Barbiturates and certain BD’s can be used. Phenobarbitone, clonazepam and clobazam all have selective anticonvulsive effects. BD’s like Diazepam and Lorazepam can be used as an anticonvulsant in patients with status epilepticus.

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

• The mechanism of action is that they inhibit polysynaptic reflexes.

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

• Therapeutic doses of sedative-hypnotics can cause respiratory depression in pulmonary disease and cardiovascular depression in cardiovascular disease. High doses of sedative-hypnotics can cause death due to depression of the medullary respiratory centre.

Resources:

Brand, L. 2021. Sedative Hypnotic drugs. Study Unit 2[PowerPoint Presentation]. Unpublished lecture notes on eFundi, FKLG 312. Potchefstroom, NWU.