carbamazepine in serum/plasma

Indications: monitoring therapy with carbamazepine - drug overdose - *monitoring medical compliance - therapeutic drug monitoring - prophylactic management of seizures, epilepsy - partial seizures - mixed partial seizure disorder - bipolar disorder (Equetro), mania - attention-deficit hyperactivity disorder (ADHD) - trigeminal neuralgia - diabetic neuropathy - neurogenic pain syndromes - alcohol abuse - cocaine abuse Reference values: - Therapeutic Range: 8-12 ug/mL - Toxic Range: > 12 ug/mL Clinical significance: 1) carbamazepine is used in the treatment of a) generalized tonic-clonic seizures b) partial seizures c) partial-complex seizures d) pain associated with trigeminal neuralgia 2) after oral administration, carbamazepine is rapidly absorbed but shows wide dual variability 3) toxicity associated with excessive carbamazepine is characterized by a) blurred vision b) nystagmus c) ataxia d) drowsiness e) diplopia 4) adverse effects at therapeutic concentrations include a) development of an urticarial rash (which usually disappears upon discontinuation of the drug) b) suppression of hematopoiesis 1] leukopenia 2] thrombocytopenia, or 3] aplastic anemia c) SIADH Principle: The unique reagents in this methodology are the matched lots of anticarbamazepine antibody & the carbamazepine - glucose-6- phosphate dehydrogenase conjugate. The reaction sequence, in two steps, is as shown: CRBAM Ab CRBAM 1) Ab + + --------> + + CRBAM-G6PD CRBAM-G6PD AbCRBAM-G6PD (active) (INHIBITED) glucose-6-phosphate CRBAM-G6PD 6-phosphogluconolactone + NAD⁺ NADH (absorbs @ 340 nm) Where: Ab = Anticarbamazepine antibody CRBAM = Carbamazepine CRBAM-G6PD = Carbamazepine - glucose-6-phosphate dehydrogenase conjugate The concentration of carbamazepine determines the amount of carbamazepine glucose-6-phosphate dehydrogenase conjugate that is bound to anticarbamazepine antibody. The unbound conjugate catalyzes the oxidation of glucose-6-phosphate with the simultan- eous reduction of NAD⁺ to NADH more rapidly than does the bound conjugate. The rate of increase of absorbance at 340 nm due to the increase in NADH is related to the carbamazepine concen- tration by means of a standard curve, or mathematical function. Specimen: Patient preparation: No special patient preparation is required. Plasma can be used. Collect sample in a green top vacutainer & centrifuge specimen. Serum is the specimen of choice. Serum samples can be collected in a red top vacutainer or red top microtainer. Serum samples can be stored at room temperature for several hours. If frozen at -20C, samples containing carbamazepine is stable for at least 1(one) year. Hemolysis & icterus do not interfere with this method. Minimum sample size 0.6 milliliters:with an optimum size of 1.5 milliliters or larger.

Specific

carbamazepine bound in serum/plasma carbamazepine free in serum/plasma

General

carbamazepine in body fluid therapeutic drug measurement

References

Kaplan, L., & Pesce, A., Clinical Chemistry:theory, analysis, & correlation, C. V. Mosby Co., St. Louis, MO., 1984, pp. 1340.
Tietz, N., Fundamentals of Clinical Chemistry, 3rd edition W. B. Saunders Co., Philadelphia, 1987, pp. 854.
Tietz, N., Textbook of Clinical Chemistry, W. B. Saunders Co., Philadelphia, 1986, pp. 1634, 1635-1636.
ACA IV Discrete Clinical Analyzer Instrument Manual, Volume 1:Operation, DuPont Company, Wilmington, Delaware, 1984.
ACA IV Discrete Clinical Analyzer Instrument Manual, Volume 3:Chemistry, DuPont Company, Wilmington, Delaware, 1984.
Package Insert, EMIT AED Calibrators, Syva Company, Palo Alto, CA.
Carbamazepine Laboratory Test Directory ARUP: 90260
Panel of 3 tests Laboratory Test Directory ARUP: 90615
Mini Panel of 2 tests: Carbamazepine, Total . Carbamazepine 10-11 Epoxide Laboratory Test Directory ARUP: 92211

Component-of

carbamazepine free/total in serum/plasma

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