Adverse effects of benzodiazepines

Both anxiolytic and hypnotic benzodiazepines worsen motor skills, attention and memory. Some short and long term adverse effects of benzodiazepines include:

• oversedation -
  • the most common dose related unwanted side effect
  • symptoms include drowsiness, poor concentration, incoordination, muscle weakness, dizziness and mental confusion
  • patients should be warned that they may feel slightly sedated at the start of the treatment (especially immediately after their dose) and this will diminish after a couple weeks of treatment
  • this is more prominent and persists for a long time in the elderly and may result in falls and fractures
  • people who are driving or operating machinery should be warned about accidents due to this adverse effect
• drug interaction
  • patients taking benzodiazepines should be warned about interaction with the following drugs
    • some antidepressants e.g. amitriptyline
    • major tranquillisers or neuroleptics e.g. prochlorperazine, trifluoperazine
    • anticonvulsants e.g. phenobarbital, phenytoin, carbamazepine
    • sedative antihistamines e.g. diphenhydramine, promethazine
    • opiates (heroin, morphine, meperidine)
    • alcohol
• memory impairment
  • there is impaired acquisition of new information
  • impairment of “episodic memory” - remembering recent events, when they occurred and their sequence in time may be deficient
  • other features of memory such as memory for words, ability to remember a telephone number for a few seconds, and recall of long-term memories are not affected
• paradoxical stimulant effect
  • may cause increased anxiety, insomnia, nightmares, hallucinations at the onset of sleep, irritability, hyperactive or aggressive behaviour, and exacerbation of seizures in epileptics
  • frequently seen in anxious and aggressive individuals, children, and the elderly
  • paradoxical reactions are more prone in patients on benzodiazepine who use alcohol
• depression
  • usually appears after prolonged benzodiazepine use
  • patients often complain of “emotional blunting” - inability to feel normal pleasure or pain due to inhibition of arousal
• adverse effects in the elderly
  • older people are more susceptible to the central nervous system depressant effects of the drug when compared to the younger people
  • may cause - confusion, night wandering, amnesia, ataxia, hangover effects and "pseudodementia" (erroneously diagnosed as Alzheimer’s disease)
• adverse effects in pregnancy
  • since benzodiazepine cross the placenta, even therapeutic dosages at late stages of pregnancy may result in neonatal complications
• dependence -
  • benzodiazepines are considered to be addictive drugs
  • both psychological and physical dependence may occur within a few weeks or months of regular or repeated use

Reference:

• (1) National Addiction Centre, King's College London and School of Social and Community Medicine 2011. The changing use of prescribed benzodiazepines and z-drugs and of over-the-counter codeine-containing products in England: a structured review of published English and international evidence and available data to inform consideration of the extent of dependence and harm.
• (2) Ashton, C.H.  2002. Benzodiazepines: how they work and how to withdraw. The Ashton Manual