title: Determination of serum carbamazepine concentration using dried blood spot specimens for resource-limited settings.
abstract: OBJECTIVE
  Carbamazepine (CBZ) is a commonly used anti-epileptic in rural hospitals in India. These hospitals lack the facilities to measure CBZ concentration; however, in larger hospitals this is performed using high performance liquid chromatography (HPLC). Dried blood spot (DBS) represents a feasible matrix for safe transportation by post/courier. This study was to determine whether the concentration of CBZ in serum can be predicted from that measured in DBS using an inexpensive HPLC method and inexpensive standard filter paper.
  
  
  METHODS
  CBZ in serum and DBS from 80 epileptic patients were measured using a validated HPLC assay. The data was then randomly divided into two groups; simple Deming regression was performed with the first group and validation was performed using the second.
  
  
  RESULTS
  There was a good correlation between the serum and DBS concentrations (r = 0.932) in the first group. The regression equation obtained was: predicted serum concentration = DBS concentration x 0.83 + 1.09. In the validation group, the correlation between the predicted and actual serum concentrations was also good (r = 0.958), and the mean difference between them was only 0.28 μg/ml (p = 0.8062). The imprecision and bias in both the groups were acceptable.
  
  
  CONCLUSIONS
  Using inexpensive materials, serum CBZ concentrations can be accurately predicted from DBS specimens. This method can be recommended for the therapeutic drug monitoring of CBZ in resource-limited settings.
authors.affiliation: a Department of Pharmacology and Clinical Pharmacology , Christian Medical College , Vellore , Tamil Nadu , India.
authors.forename: Saibal
authors.initials: S
authors.lastname: Das
authors.affiliation: a Department of Pharmacology and Clinical Pharmacology , Christian Medical College , Vellore , Tamil Nadu , India.
authors.forename: Denise H
authors.initials: DH
authors.lastname: Fleming
authors.affiliation: a Department of Pharmacology and Clinical Pharmacology , Christian Medical College , Vellore , Tamil Nadu , India.
authors.forename: Binu S
authors.initials: BS
authors.lastname: Mathew
authors.affiliation: a Department of Pharmacology and Clinical Pharmacology , Christian Medical College , Vellore , Tamil Nadu , India.
authors.forename: Blessed
authors.initials: B
authors.lastname: Winston A
authors.affiliation: b Department of Neurological Sciences , Christian Medical College , Vellore , Tamil Nadu , India.
authors.forename: Appaswamy T
authors.initials: AT
authors.lastname: Prabhakar
authors.affiliation: b Department of Neurological Sciences , Christian Medical College , Vellore , Tamil Nadu , India.
authors.forename: Mathew
authors.initials: M
authors.lastname: Alexander
mesh_terms: D000293:Adolescent; D000328:Adult; D000927:Anticonvulsants / Q000097:blood* / Q000627:therapeutic use; D002220:Carbamazepine / Q000097:blood* / Q000627:therapeutic use; D002648:Child; D002851:Chromatography, High Pressure Liquid; D003430:Cross-Sectional Studies; D016903:Drug Monitoring / Q000379:methods*; D004827:Epilepsy / Q000188:drug therapy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D055815:Young Adult
chemical_list: D000927:Anticonvulsants; D002220:Carbamazepine
keywords: Carbamazepine (CBZ); anti-epileptic; dried blood spot (DBS); high performance liquid chromatography (HPLC); therapeutic drug monitoring (TDM)