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Age-related differences in susceptibility to toxic effects of valproic acid in rats

Parvaneh Espandiari1, Jun Zhang, Laura K Schnackenberg

  • 1FDA, Center for Drug Evaluation and Research, Silver Spring, MD 20993, USA. parvaneh.espandiari@fda.hhs.gov

Journal of Applied Toxicology : JAT
|November 13, 2007
PubMed

Insights

Valproic acid (VPA) toxicity varies by age in young rats, with distinct patterns of liver injury and other effects observed across different age groups. A multi-age model is crucial for understanding age-dependent drug toxicity.

Area of Science:

  • Toxicology
  • Pharmacology
  • Pediatric Medicine

Background:

  • Valproic acid (VPA) is a widely used antiepileptic drug with known pediatric hepatotoxicity.
  • Understanding age-related differences in drug toxicity is critical for safe pediatric prescribing.

Purpose of the Study:

  • To evaluate a multi-age Sprague-Dawley rat model for assessing age-dependent liver injury from valproic acid (VPA).
  • To identify specific toxicological profiles associated with different age groups exposed to VPA.

Main Methods:

  • Administration of VPA at varying doses (160-650 mg/kg) to Sprague-Dawley rats aged 10, 25, 40, and 80 days for 4 days.
  • Assessment of toxicity through clinical signs, lethality, hematological parameters (platelets, blood urea nitrogen), liver enzymes (ALT, ALP), serum total protein, urine creatine, and histopathological examination of liver and spleen.
  • Utilized Principal Component Analysis (PCA) on urine spectra to differentiate age-group responses.

Main Results:

  • All age groups exhibited VPA-induced toxicity, but with distinct patterns.
  • Significant lethality occurred in younger rats (10- and 25-day-old) at high VPA doses.
  • Age-specific effects included decreased platelet counts (10-, 25-day-old), growth rate reduction (40-day-old), increased urine creatine (80-day-old), and varied hepatic/splenic lesions, most severe in 10- and 80-day-old rats.
  • Biochemical markers like BUN, ALT, and ALP showed significant changes in 10-day-old pups, while serum total protein decreased in older rats (40-, 80-day-old).
  • PCA confirmed distinct clustering of urine spectra by age group.

Conclusions:

  • The multi-age rat model effectively demonstrated age-dependent differences in VPA toxicity.
  • Vulnerability to VPA-induced liver injury and other toxicities varies significantly across developmental stages in rats.
  • This model is suitable for comprehensively studying age-related changes in drug toxicity in pediatric populations.

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