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18 Cards in this Set
- Front
- Back
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What is Therapeutic Drug Monitoring?
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Therapeutic drug monitoring is the measurement of specific drugs at timed intervals in order to maintain a relatively constant concentration of the medication in the bloodstream. Drugs that are monitored tend to have a narrow "therapeutic index" – the blood level required to be effective is close to the level that causes significant side effects and/or toxicity.
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What are the goals of TDM?
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To increase efficacy of treatment
To increase safety of treatment To decrease global costs of treatment |
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What criteria must be me for TDM?
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1) Proven relationship between blood and tissue drug concentrations and pharmacological effect
2) Known therapeutic and toxic concentration ranges 3) Low therapeutic index 4) Highly variable pharmacokinetics 5) Permanent/dangerous side fx 6) No clear clinical endpoint of drug's action |
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What are the clinical indications for TDM?
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- No therapeutic effect
- Toxic effect suspected - Impaired liver or renal function - Drug-drug interactions in pharmacokinetic phase |
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What are some commonly monitored drugs?
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1) Digoxin/Digitoxin
2) Carbamazepine, Phenytoin, Phenobarbital, Valproic acid 3) Theophylline 4) Amikacin, Netilmycin, Vancomycin 5) Cyclosporine A, Tacrolimus 6) Methotrexate |
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When is steady state achieved? When is sampling carried out?
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After approximately four half-times. The time to steady state is independent of dosage.
After absorption and distribution of the last dose. (usually before administrating the next dose) |
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What is the therapeutic range?
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The range of drug concentrations in blood with the highest probability of therapeutic effect and the lowest risk of toxic effects in the majority of population
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What are the indications for TDM with Digoxin?
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Renal failure
Severe heart failure Advanced age Thyroid problems Toxicity symptoms Drug interactions |
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What is the time to steady state for digoxin? Therapeutic range? Toxic concentrations ?
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7-8 days.
0.8-1.2 ng/mL >2 ng/ml *Increased inotropic and chronotropic effects on the heart* |
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What are the indications for TDM for theophylline?
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Age : neonatal and elderly
Liver diseases Smoking Advanced heart failure Drug interactions (H2 blockers, macrolides) * Bronchodilator* |
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What is the time to steady state for theophylline? Therapeutic and toxic concentrations?
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2-6 days
10-20 ug/mL >20 ug/ml and severe >35ug/mL |
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Indications for TDM for Carbamazepine
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In children
Pregnancy Liver diseases Toxicity symptoms Drug interactions (phenytoin, phempbarbital) *Antiepileptic agent* |
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Time to steady state for carbamazepine? Therapeutic and toxic concentrations ?
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2-4 weeks
4-10 ug/mL >12 ug/mL |
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What is the active metabolite of carbamazepine?
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10,11-epoxide
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Indications for TDM for valproic acid? When should monitoring of free fraction occur?
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Children
Liver disease Toxicity symptoms Monitoring of free fraction: - pregnancy - hypoalbuminemia - uremia *antiepileptic* |
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Steady state time , therapeutic and toxic concentrations for valproic acid?
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2-3 days
50-100 ug/mL >150 ug/mL |
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Indications for TDM with cyclosporine A
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Liver diseases
Malabsorption syndromes Early after transplantation Toxicity symptoms *Immunosuppressant* |
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Time to steady state for cyclosporine A? Minimal effective concentration? Therapeutic range? Toxic concentrations?
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5-7 days. Measured at predose , 2 and 4 hours after the last dose.
100 ng/mL 100-450 ng/mL >600 ng/mL |
