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Side Effects of


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Description: Antispasmodics are a class of drugs that typically suppress muscle spasms. They are either antimuscarinic drugs or smooth muscle relaxants. Antimuscarinic drugs include hyoscine and atropine, whereas smooth muscle relaxants include alverine and mebeverine. These drugs are used in the treatment of a number of diseases. However, they are primarily used to treat irritable bowel syndrome (IBS) (World Journal of Gastroenterology “Role of antispasmodics in the treatment of irritable bowel syndrome,” May 2014).

Serious Side Effects of Antispasmodics

Most patients do not suffer adverse reactions when taking antispasmodics and they are generally well tolerated drugs. However, some patient can have drug hypersensitivity reactions which may prove fatal.

Common Side Effects of Antispasmodics

Antispasmodics are generally well-tolerated. Common side effects include:

  • Heartburn
  • Constipation
  • Dry mouth
  • Tremor
  • Erectile dysfunction
  • Difficulty passing urine
  • Seizures
  • Anemia
  • (Database of Abstracts of Reviews of Effects [DARE] “Effect of antispasmodic agents, alone or in combination, in the treatment of Irritable Bowel Syndrome: systematic review and meta-analysis,” 2011).

    Individual Differences in Susceptibility to Side Effects

    Reducing the risk of developing these side effects is an area of development in medicine today. The interpatient variability of side effect profiles is partially accounted for by pharmacogenetics. This is the individual genomes of patients and how these interact with the drugs they take. Polymorphisms in the genes that code for enzymes and receptors that interact with antispasmodics will increase or decrease an individual’s probability of developing adverse reactions.

    Understand Your Risks with the Rxight® Genetic Test

    Identifying these polymorphisms is therefore important for clinical decision making. An individual with a known polymorphism that increases the probability of developing side effects may not be prescribed an antispasmodic or might be started on a lower dose. Unfortunately, routine genomic screening is not done by most healthcare providers. MD Labs provides this service with our genetic testing product Rxight®, which sequences 18 genes to establish which polymorphisms an individual holds and what drugs are likely to cause side effects or be ineffective. The results can then guide your prescriber(s) in tailoring your pharmacotherapy precisely to you instead of relying on trial and error.

    Contributors to this Article:
    Michael Sapko, MD, PhD; Deborah Kallick, PhD, Medicinal Chemistry

    Antispasmodics Tested Include:

    • Oxybutynin (Ditropan)

    Read more about Rxight® Genetic Testing For Drug Metabolism