THERAPEUTIC DRUG MONITORING PROCESS.pptx

TDM

1. THERAPEUTIC DRUG MONITORING PROCESS Presented By, Kavyashree 19Q0763

2. DEFINITION TDM is a measurement of drug concentrations usually in the blood or plasma that facilitates adjustment of dosage to produce a desired response. It is a multidisciplinary function and required collaboration and communication between scientists, clinicians, nurses and pharmacologist. 2

3. PROCESS OF TDM Decision to request drug level Biological sample The request Laboratory measurement Result communication by laboratory Clinical interpretation Therapeutic management 3

4. 1. DECISION TO REQUEST DRUG LEVEL Decision will be based on proper reasons: Suspected toxicity Lack of response/compliance. To assess t herapy following change in dosage Change in clinical state of patient. Potential drug interactions due to concomitant m edications. 4

5. 2.THE BIOLOGICAL SAMPLE After decision is made, biological sample is collected for to provide measurement. Serum or plasma samples are usually collected for TDM. Serum separator tubes should be avoided as lipophilic drugs can dissolve in gel barrier. Blood sample should be collected once the drug concentration have attained steady state(SS) Levels approximating SS may be reached earlier if a loading dose has been administered. 5

6. However, drugs with long half-lives should be monitored before SS is achieved to ensure that individuals with impaired metabolism or renal excretion are not in the risk of developing toxicity at the initial dosage prescribed. If toxicity is suspected the concentration should be measured as soon as possible. Blood samples should be collected in elimination phase rather than absorption/distribution phase Usually blood samples are collected at the end of the dosage interval. For antibiotics given intravenously, peak concentrations are also measured. Usually drug concentrations are monitored in venous blood, serum, or plasma and it is important t hat the appropriate matrix is assayed. 6

7. 3.REQUEST Following details must be effectively communicated to members of TDM team with a drug assay request: Timing of sample. Dosage regimen Patient demographics (age, sex, ethnicity etc.) Co-medications, if any - Indication for monitoring. PK & therapeutic range of drug. When a drug which is commonly measured for TDM is suspected of causing toxicity, it is very important for requesting clinicians to clearly communicate the expectation of a high concentration and need for a rapid feedback of results 7

8. 4. LABORATORY MEASUREMENT A quality drug assay should be performed within a clinically useful time frame. The assay procedure should be validated one. Wherever possible assay procedure should be evaluated with an external quality assurance program. Senior laboratory staff should verify the assay results in light of clinical request. Ideally the results of the assay should be available to the clinician before the next dose is given. 8

9. The analytical methodology employed should ideally: Distinguish between compounds of similar structure- unchanged drug and metabolites. Detect small amounts. Be simple enough to use as a routine assay. Be unaffected by other drugs administered simultaneously. 9

10. Various analytical techniques available are: Spectrophotometry and Fluorimetry TLC HPLC & GLC Radio Immunoassay Enzyme Immunoassay Fluorescence polarization Immunoassay (FPIA) 10

11. 5. RESULT COMMUNICATION BY LABORATORY: The assay results should be communicated as quickly as possible once it is verified by the senior laboratory personnel. The drug concentrations measured are generally reported in mass or molar units To relate concentration back to dose, mass units are preferable. The result should clearly state the therapeutic concentration range for the drug assayed. 11

12. 6. CLINICAL INTERPRETATION Clinical interpretation can ‘ add value ’ and convert ‘ therapeutic measurement service ’ into ‘ therapeutic drug monitoring service ’. Just relating a drug concentration to a published therapeutic range is not an adequate interpretation. Concentration must always be interpreted in the light of clinical response, individual patient demographics and dosage regimen used. Therapeutic ranges are available but should only be used as a guide. 12

13. 7. THERAPEUTIC MANAGEMENT The clinician caring for a patient will modify a drug dosage regimen in light of all available information. Physicians usually accept and implement recommendations of TDM team. Hence, remember of the TDM team with appropriate clinical expertise should be available to conduct a successful TDM. 13

14. QUESTIONS 5 mark Describe the protocol for TDM of a drug. 2 mark Write the protocol for TDM of a drug. 14

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