Therapeutic Drug Monitoring Quiz

Therapeutic Drug Monitoring (TDM) Overview

• Primary goal of TDM is to optimize drug therapy by maintaining drug concentrations within therapeutic ranges.
• Monitoring drug levels helps prevent toxicity or subtherapeutic dosing.

Drug Concentration and Effects

• Low drug concentration leads to ineffective treatment, potentially resulting in disease progression.
• High drug concentration can cause adverse effects or toxicity, endangering the patient’s health.

Minimum Effective Concentration (MEC)

• MEC represents the lowest drug concentration required to achieve the desired therapeutic effect.

Therapeutic Window

• Defined as the range between the MEC and the minimum toxic concentration (MTC).
• Characterized by the drug's specific range in which it is effective without causing harmful side effects.

Side Effects and Monitoring

• The concentration that produces unwanted side effects is known as the minimum toxic concentration (MTC).
• TDM is crucial for individualizing dosages to ensure effectiveness while minimizing side effects.

Indications for TDM

• TDM is warranted in specific scenarios, such as narrow therapeutic indices, variable pharmacokinetics, or when the disease state affects drug metabolism.

Characteristics of Drugs Requiring TDM

• Typical drugs needing TDM include those with narrow therapeutic ranges, large inter-patient variability, and those prone to drug interactions.

Biological Matrix for Measuring Drug Levels

• Serum is commonly used to measure the therapeutic range of digoxin, a drug that requires careful monitoring.

Consequences of Subtherapeutic Levels

• Subtherapeutic levels of digoxin can lead to heart failure or other complications due to insufficient therapeutic effects.

Causes of Alterations in Drug Concentration

• Common causes for changes in serum drug concentration include drug interactions, variations in patient metabolism, and organ dysfunction.

TDM for Organ Failure Patients

• TDM is especially important for patients with major organ failure, as impaired function significantly alters drug pharmacokinetics.

Quinidine and Digoxin

• Quinidine can increase the renal clearance of digoxin, leading to decreased drug levels and potentially reduced therapeutic effects.

Timing of TDM

• TDM should be performed for drugs with a narrow therapeutic range at specific intervals and after any dosage adjustments to ensure efficacy and safety.