Evidencebased implementation of free phenytoin therapeutic. Nov 20 page 1 of 10 medicines formulary therapeutic drug monitoring contents. Oct 28, 2019 therapeutic drug monitoring of serum phenytoin concentrations usually recommended to guide dosing. However, total phenytoin levels can be misleading in patients with factors such as low plasma albumin that alter the free unbound. The concordance data was also broken down into patients who did or did not have documented seizures within 24 hours of the blood draw for phenytoin drug level additional file 1. To evaluate w h e t h e r patients admitted to the hospital with oral p h e n y t o i n overdose should receive cardiac telemetry monitoring.
T1 evidencebased implementation of free phenytoin therapeutic drug monitoring. Therapeutic drug monitoring of phenytoin by measurement of plasma concentrations is often employed to optimize clinical efficacy while avoiding adverse effects. People on phenytoin should be monitored for any changes in mood, the development or worsening depression, andor any thoughts or behavior of. Patients with serum drug concentrations on noncovered services are identified on a daily basis utilizing sunrise clinical manager scm. Suggestions for drug monitoring in adults in primary care. Dilantin phenytoin sodium food and drug administration. However, this medicine can make absence or petit mal seizures happen more frequently.
Dilantin phenytoin sodium 100 mg extended oral capsule. Phenytoin has very challenging pharmacokinetic properties. Therapeutic serum concentrations and sampling guidelines 228 drug usual sample time therapeutic serum concentration physicians routine inpatient orders comments lithium pre level 30 min. Some of the factors complicating phenytoin dosing include a narrow therapeutic window, high degree of. Okay, so the drugs you really kinda need to know for nclex and their therapeutic level are digoxin, lithium, theophylline and phenytoin. E v e r s, m d, f a c e a m i r i z h a r, m d, a n d a r s h a d a q i l, m d, t r e n t o n, n. Therapeutic drug monitoring medicines formulary, version 7 principal author. Methods and materials the analysis of antiepileptic drugs was performed using. Figure s4 and those on phenytoin monotherapy for seizure therapy versus those also being treated with additional antiepileptic drugs additional file 1. For most patients the optimal serum level is within a range of 4080. The chemical name is sodium 5,5diphenyl2, 4imidazolidinedione, having the following structural formula.
Phenytoin sodium is related to the barbiturates in chemical structure, but has a fivemembered ring. Phenytoin base eg, oral suspension, chewable tablets contains 8% more drug than phenytoin sodium 92 mg base is equivalent to 100 mg phenytoin sodium. Therapeutic drug monitoring of phenytoin by measurement of plasma. Therapeutic drug monitoring tdm is generally defined as the clinical laboratory measurement of a chemical parameter that, with appropriate medical interpretation, will directly influence drug prescribing procedures.
Research article open access clinical decision support. Effect of phenytoin, phenobarbital and valproic acid on. Narrow therapeutic index drugs are drugs where small differences in dose or blood concentration may lead to serious therapeutic failures andor adverse drug reactions that are life. This article is authors endeavour to summarize facts in different publications on tdm of carbamazepine. Various studies claim the usefulness of tdm of carbamazepine but clearcut guidelines for tdm are still lacking.
Its main focus is on drugs with a narrow therapeutic range, i. Some of the factors complicating phenytoin dosing include a. In a clinical trial of adults with inhospital status epilepticus, intravenous lorazepam was superior to intravenous phenytoin. The measurement of plasma concentrations of drugs given in therapy therapeutic drug monitoring, tdm is useful for a small number of compounds for which pharmacological effects cannot be easily assessed and for which the margin between adequate dosage and potentially toxic dosage is small. Loading dose of 10 15mgkg phenytoin by iv infusion. Also, the therapeutic drug monitoring tdm laboratory provides an electronic report of all completed serum drug concentrations of patients admitted to the hospital twice daily. Mar 28, 2019 this drug may be administered by iv or im injection. Drugs with a narrow therapeutic index where therapeutic drug levels do not differ greatly from levels associated with serious toxicity should be monitored. However, total phenytoin levels can be misleading in patients with factors such as low plasma. Patients who have impaired clearance of a drug with a narrow therapeutic index are candidates for drug monitoring. To prevent its toxicity and ensure efficacy, continuous therapeutic monitoring is required. The prescribing and monitoring of phenytoin in epilepsy. This document complies with the royal cornwall hospitals nhs trust service.
Therapeutic drug monitoring of antiepileptic drugs. Definition drug therapy monitoring, also known as therapeutic drug monitoring tdm, is a means of monitoring drug levels in the blood. Thus, for some anticonvulsants, notably phenytoin, antiinfective agents. Feb 14, 2012 the concordance data was also broken down into patients who did or did not have documented seizures within 24 hours of the blood draw for phenytoin drug level additional file 1. Otherwise, tdm refers to the individualization of drug dosage by maintaining plasma or blood drug concentrations within a. Each antacid was administered as 160 meq at 1 and 3 hr after each meal and at bedtime on the day phenytoin was given.
Phenytoin is a narrow therapeutic drug there is little difference between a sub therapeutic. Cardiac monitoring after phenytoin overdose m a r t i n l. And a lot of times, phenytoin is gonna be tested as well. Racgp just a repeat when drug monitoring is indicated. Basic data information for interpretation time of blood sampling with respect to the last dose duration of treatment with present dose dosing schedule age and gender of patient other drug therapies disease states objectives of monitoring pharmacokinetic parameters of the drug. Guide for drug level monitoring of commonly used medications.
The consultant in the acute medical unit asks you to prescribe a phenytoin loading dose and maintenance regimen. Gareth malson updated with approvals from wirral drug and therapeutics committee. Check albumin level concurrently with phenytoin level albuminadjusted phenytoin level may be higher than reported i. Dosage adjustments and closer serum monitoring may be necessary when switching dosage forms. Some of the factors complicating phenytoin dosing include a narrow therapeutic window, high degree of protein binding, and nonlinear pharmacokinetics. Therapeutic free phenytoin monitoring springerlink. This is most commonly accomplished by measurement of total phenytoin plasma concentrations. Clinical guideline for the use of phenytoin in epilepsy final.
Pdf therapeutic drug monitoring of phenytoin is carried out to ensure effective and safe levels. Therapeutic drug monitoring of antiepileptic drugs in. Therapeutic drug monitoring is generally only indicated when medications have specific characteristics eg. Sim analisys 140,00140,00 was added as additional reference ion. Therapeutic levels of phenytoin are 4080 umollitre. It works by reducing the spread of seizure activity in.
Clinical decision support of therapeutic drug monitoring. Mar 06, 2009 pioneers of drug monitoring in the 1970s focused on adverse drug reactions and demonstrated clearly that by constructing therapeutic ranges, the incidence of toxicity to drugs such as digoxin, phenytoin, lithium, and theophylline could be reduced. A number of drugs show a narrow therapeutic range and for these drugs therapeutic drug level monitoring is required chapter 2. The majority of laboratories measure total phenytoin concentration for. Phenytoin is used to prevent and control seizures also called an anticonvulsant or antiepileptic drug. Because of its narrow therapeutic index, its saturable elimination kinetics, and its concentrationdependent side effects, monitoring of drug plasma concentrations is recommended as a guide to dosage individualization. This has led to an increasingly widespread application of therapeutic drug monitoring tdm of aeds, making aeds among the most common medications for which tdm is performed. The mean area under the curve auc was significantly decreased by amh p phenytoin has been investigated as a treatment for more than 100 diseases. Clinical decision support of therapeutic drug monitoring of phenytoin. Drug therapy monitoring definition of drug therapy. The mean area under the curve auc was significantly decreased by amh p dilantin, dilantin125 is an oral and injectable drug prescribed for the treatment of seizures. Phenytoin has been investigated to treat thought, mood and behavior disorders, cardiovascular disorders, neuro muscular disorders, gastrointestinal disorders, and endocrine disorders. The majority of laboratories measure total phenytoin concentration for therapeutic drug monitoring. Therapeutic drug monitoring of phenytoin is necessary to ensure therapeutic and nontoxic levels.
Hypoalbuminemia, renal failure, and interactions with other highly proteinbound drugs e. Phenytoin may increase risk of suicidal thoughts or behavior. Therapeutic drug monitoring of phenytoin is carried out to ensure effective and. Therapeutic drug monitoring of phenytoin is carried out to ensure effective and safe levels. And, most important are gonna be these first three, digoxin, lithium and theophylline. This article is from bmc medical informatics and decision making, volume 12. There are different methods to detect carbamazepine in plasma i. Therapeutic drug monitoring tdm is the use of drug concentration measurements in. Phenytoin is also associated with induction of reversible iga deficiency. May 01, 2001 phenytoin is a primary anticonvulsant drug that is used for the prophylaxis of generalized tonicclonic and partial seizures. Guidelines for therapeutic drug monitoring q pulse reference no.
In routine clinical practice, serum drug level monitoring and optimisation of a dosage regimen require the application of clinical pharmacokinetics. Therapeutic drug monitoring of antiepileptic drugs in serum. The monitoring parameters cited are derived from a range of guideline sources, other. Purpose tdm is employed to measure blood drug levels so that the most effective dosage can be determined, with toxicity prevented. This medicine is available in different forms, including dilantin, phenytek, or generic phenytoin. A guide to therapeutic drug monitoring melissa faye. Therapeutic drug monitoring of phenytoin in critically ill. In hospitalized patients with status epilepticus, intravenous lorazepam is the drug of choice for initial emergency therapy.
Cardiac monitoring after phenytoin overdose pdf free download. Therapeutic drug monitoring authorstream presentation. Therapeutic drug monitoring therapeutic drug monitoring tdm is the use of drug concentration measurements in body fluids as an aid to the management of drug therapy for the cure, alleviation or prevention of disease. Phenytoin has been known to cause drug induced lupus. Do not administer as a rapid iv infusion, as severe hypotension and bradycardia may occur. Therapeutic drug monitoring of phenytoin by simple, rapid. Phenytoin is an antiepileptic agent which is effective for tonicclonic and focal seizures 1. Clinical decision support of therapeutic drug monitoring of. Nhs tayside phenytoin prescribing and monitoring guideline. Due to the special pharmacokinetic features of phenytoin, accurate titration and use of this drug is very difficult without serum level monitoring. The monitoring of therapeutic drugs is especially for personalizing medicine in ageing population and to optimize the efficacy of drugs in children as there are differences in absorption, disposition and pharmacological effects of most drugs between adult and children.
All phenytoin results are reported in the following panel, with an adjusted phenytoin value. However, total phenytoin levels can be misleading in. Where this cannot be done, therapeutic drug monitoring is used in two major situations 3. Nhs grampian acute sector summary guideline for therapeutic drug monitoring tdm in adults version 2 antibiotic assays on the microbiology request card for serum levels, please supply details of the antibiotic level required, the time and date of the sample. Summary guideline for therapeutic drug monitoring tdm in adults. Therapeutic plasmaphenytoin concentrations reduced in first 3 months of life because of reduced protein binding.
Research article open access clinical decision support of. It is a medicine that has been approved by the food and drug administration to treat tonic clonic grand mal and complex partial seizures. Updated with approvals from wirral drug and therapeutics committee. When a change in the dosage form or brand is prescribed, careful monitoring of phenytoin serum levels should be carried out.
Generally, administered as 1g phenytoin diluted in 100ml sterile 0. It is hard to get a simple, accurate, rapid, easily available, economical and highly sensitive assay in one method for therapeutic monitoring of phenytoin. Therapeutic drug monitoring tdm is a branch of clinical chemistry and clinical pharmacology that specializes in the measurement of medication levels in blood. One of these is therapeutic drug monitoring of antiepileptic medications such as.
941 1232 47 343 1484 184 674 1013 400 439 846 99 1235 937 81 700 1471 998 392 559 44 1409 1340 1445 478 1562 1473 1079 918 265 703 1308 1429 1041 545 1170 1105 685 121 145 718 1334 916 256 1200 1195