Opinion

Genetics and the side effects of psychoactive medicines

Catherine Clarke says testing patients’ genotypes could help to identify and minimise potential neurotoxic responses and adverse drug reactions
Pharmogenetics

Catherine Clarke says testing patients genotypes could help to identify and minimise potential neurotoxic responses and adverse drug reactions.

I believe genotype testing pharmacogenetic screening is essential for the safety and well-being of patients taking psychiatric medication. I also believe nurses have a right to know why some patients respond therapeutically to medication and others deteriorate.

Within general medicine, genetic screening is undertaken prior to prescribing medication for certain diseases, providing patients with a safety net against life-threatening adverse drug reactions. Screening does not take place in relation to mental health problems, leaving patients without a medication safety net which I believe to be unacceptable and discriminatory.

Research shows that selective serotonin reuptake inhibitors (SSRIs) can induce akathisia, insomnia, suicide/suicide ideation, psychosis, homicide/ideation and mania, while they are also

...

Catherine Clarke says testing patients’ genotypes could help to identify and minimise potential neurotoxic responses and adverse drug reactions.

I believe genotype testing – pharmacogenetic screening – is essential for the safety and well-being of patients taking psychiatric medication. I also believe nurses have a right to know why some patients respond therapeutically to medication and others deteriorate.


Understanding patient genetics could help in treating toxic reactions. Picture: iStock

Within general medicine, genetic screening is undertaken prior to prescribing medication for certain diseases, providing patients with a safety net against life-threatening adverse drug reactions. Screening does not take place in relation to mental health problems, leaving patients without a medication safety net – which I believe to be unacceptable and discriminatory.

Research shows that selective serotonin reuptake inhibitors (SSRIs) can induce akathisia, insomnia, suicide/suicide ideation, psychosis, homicide/ideation and mania, while they are also linked with genetic variations (Lucire and Crotty 2011, Piatkov et al 2012).

These toxic reactions occur because some patients metabolise SSRIs inefficiently. I maintain that screening patients prior to prescribing SSRIs would protect vulnerable people from these toxicities.

The Diagnostic and Statistical Manual (American Psychiatric Association 1994) stipulates that a mental health diagnosis must distinguish between a condition caused by medication toxicities and a mental illness. Genotype testing would fulfil this requirement in supplying an accurate diagnosis.

Prescription of inappropriate additional psychiatric medications could be avoided in patients who suffer from toxic conditions, thereby keeping them safe from incurring additional adverse drug reaction toxicities.

Genetic screening

So why is pharmacogenetic screening off the mental health radar? One reason is that it is considered to be ‘not cost effective.’ I disagree: a one-off payment of £30 for a screening test would be cost effective if compared to the cost of potential involvement of the police, ambulance service, inpatient treatment settings and social security benefits if treatment is sub-optimal.

One leading psychiatrist has said there is no evidence that screening should take place at this time. I disagree: 75% of all psychiatric medicines are metabolised by the CYP 2D6 gene pathway (Arehart-Treichel et al 2004). Between 40 and 50% of African-Americans, 50% of black people and 26% of Caucasians are ineffectual metabolisers for CYP450 2D6, the enzyme that affects metabolism of such medicines (Genelex 2017).

Perhaps the over-representation of people from black and minority ethnic backgrounds in psychiatric intensive care units and low secure units could be explained by this genetic difference (Pereira et al 2006).

The Medicines and Healthcare Products Regulatory Authority (MHRA) and the Royal college of Psychiatrists acknowledge that pharmacogenetics play a role in psychiatric medication adverse drug reactions, but both maintain more research is needed. I disagree with that conclusion, but it is true that there is currently no UK research on pharmacogenetics, psychiatric medications and adverse neurobehavioral drug reactions.

Even though the MHRA states that all selective serotonin reuptake inhibitor product information (the summary product characteristics) should reflect adverse drug reactions, pharmacogenetics information is absent.

Lack of information

Patients, doctors and all of you are in the dark about this issue, which means vulnerable patients remain unnecessarily exposed to adverse neurobehavioral drug reactions.

I believe screening would address repeated ‘trial and error’ prescribing, give an understanding of adverse neurobehavioral drug reactions and an informed diagnosis of a toxic mental health condition, and reduce costs. Screening would provide an akathisia-free environment and protect people’s physical safety, so enabling mental health staff to get on with the job in hand of helping patients to get better and live meaningful lives.

I am asking all of you to be involved with placing pharmacogenetic screening on the mental health map, to pave the way for improved mental health provision and increase your own job satisfaction.


References

  • Arehart-Treichel J (2005) Gene Testing Could Help Predict Drug Responses Clinical and Research News. Psychiatric News. American Psychiatric Association. May 20, 2005.
  • Diagnostic and statistical manual of mental disorders (DSM IV) (1994) 4th Edition. American Psychiatric Association. Washington DC.
  • Genelex (2017) Cytochrome CYP2D6 Genotyping.
  • Lucire Y, Crotty C (2011) Antidepressant-induced akathisia-related homicides associated with diminishing mutations in metabolizing genes of the CYP450 family. Pharmacogenomics and Personalized Medicine. 4, 65-81.
  • Piatkov I, Jones T, McLean M (2012) Cases of Adverse Reaction to Psychotropic Drugs and Possible Association with Pharmacogenetics. Journal of personalized medicine. 2, 149-157.
  • Pereira S, Dawson P, Sarsam M (2006) The National Survey of PICU and Low Secure Services: 1. Patient characteristics. Journal of Psychiatric Intensive Care. 2, 1, 7-12.

Catherine Clarke is a mental health carer who focuses on improving knowledge about psychiatric medications and psychological therapies

For more information you can visit her website

 

Want to read more?

Subscribe for unlimited access

Enjoy 1 month's access for £1 and get:

  • Full access to mentalhealthpractice.com
  • Bi-monthly digital edition
  • RCNi Portfolio and interactive CPD quizzes
  • RCNi Learning with 200+ evidence-based modules
  • 10 articles a month from any other RCNi journal

This article is not available as part of an institutional subscription. Why is this?

Jobs