Therapeutic Drug Monitoring

A variety of prescription and over-the-counter (OTC) medications can cause drug overdoses. Emergency and overdose drug testing is ordered for single drugs or groups of drugs by an emergency room (ER) health practitioner to detect, evaluate, and monitor a drug overdose.

Drugs and related substances that are ingested or absorbed are typically broken down (metabolised) by the liver over a period of time and then eliminated from the body, primarily in the urine. The rate at which this happens depends on a number of factors ranging from age, weight, and sex to food intake and presence of underlying diseases. Moreover, the development of toxicity depends on the type of substance absorbed or ingested.

Some substances cause symptoms only if they are present in high concentrations or above therapeutic levels. Some common examples of these include:

  • Paracetamol (Acetaminophen) - an ingredient in many over-the-counter preparations; it can cause significant liver damage if recommended doses are exceeded.
  • Aspirin (also known as salicylates)—at higher levels, it can cause an acid-base imbalance.
  • Therapeutic drugs - used to treat conditions such as heartfailure and epilepsy.

Ingestion of a variety of other drugs and chemicals may cause acute toxicity.

Overdoses caused by prescription and OTC drugs may be due to:

  • Ingestion of too much of a medication
  • Interaction of multiple drugs
  • A decrease in the body's ability to eliminate a drug and/or its metabolite; many drugs are processed by the liver; that is, the liver changes the drug into a different form, which is then eliminated from the body. If the liver or kidneys are not working properly, then the drug and/or its metabolite may build up in the body.

A classic example of an OTC drug with a toxic metabolite is acetaminophen, a common pain reliever that is also a component of a variety of other OTC and prescription medicines. One of the metabolites of acetaminophen is toxic to the liver, but the liver is able to detoxify "normal" amounts of it. However, if someone takes more acetaminophen than the liver can process, then the toxic metabolite builds up, damaging the liver and, in some cases, causing liver failure.

Paracetamol (Acetaminophen) Kit

Adaptable for use on multiple clinical chemistry systems as either a 2 reagent kit, K8003 or as a 3 reagent kit K8002. The intended use is for the quantitative measurement of paracetamol in serum / plasma as an aid to monitor and diagnose paracetamol overdose. There is no interference from up to 1g/L N-acetyl cysteine or Paracetamol metabolites. Linearity is 0.02 - 5.00 mmol/L (3 - 756 mg/L) using sera calibrators. Sera calibrators, K8100 are available separately too.

Salicylate Kit

Adaptable for use on multiple clinical chemistry systems, K9001Stable liquid ready to use reagent with no additional reagent preparation required. The intended use is for the quantitative measurement of salicylate in serum / plasma as an aid to monitor and diagnose salicylate overdose. Linearity is 0.05 - 10.00 mmol/L (6 - 1380 mg/L).

Lithium

This test measures the amount of lithium in the blood. Lithium is a drug that is used to treat bipolar disorder. Bipolar disorder is a mental condition that is characterised by cycles of depression and mania. Lithium is prescribed to even out the moods of the person with bipolar disorder and is sometimes prescribed for patients with depression who are not responding well to other medications. It may take several weeks to months for lithium to affect a person’s mood. Dosages of the drug are adjusted until a steady concentration in the blood is reached. The actual amount of drug that it will take to reach this steady state will vary from person to person and may be affected by the individual’s age, general state of health, and other medications. Lithium levels must be maintained within a narrow therapeutic range. Too little lithium and the medication will not be effective; too much and patients will experience symptoms of lithium toxicity, such as stomach ache, nausea, vomiting, diarrhoea, confusion, blurred vision, sleepiness and tremors (shaking). Extremely high levels can lead to loss of consciousness and/or seizures, and can be fatal.

Product Code: DZ116B-K - Diazyme Lithium Enzymatic Assay

Suitable for clinical chemistry systems.  More information is available from the datasheet.

Resources

CodeDescriptionMSDSInstructions for use
K8002Paracetamol (Acetaminophen) 3 Reagent Assay Kit
K8003Paracetamol (Acetaminophen) 2 Reagent Assay Kit
K9001Salicylate Test Kit
DZ116B-KDiazyme Lithium Enzymatic Assay kit
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