Itching Skin Rash during Valproic Acid Therapy in Co-Administration with Silodosin: a Case Report and Review of Literature

Mv Romano,M Marino

doi:10.4172/2155-9554.1000339

Abstract

Valproic acid (VA) is an antiepileptic drug commonly used in psychiatric setting as mood stabilizer. It is generally well-tolerated but, because of its pharmacodynamic properties, it may cause different adverse drug reactions, especially when it is co-administrated with other drugs. Here we report the case of a 65 year old man with a Bipolar Disorder type I, according to DSM V, hospitalized for a depressive relapse and treated with Valproic Acid 300 mg/day, Lorazepam 2.5 mg/day, and Elopram 40 mg/ml intravenous daily infusions. When, one week after admission, Silodosin 8 mg/day was added for the management of Benign Prostatic Hyperplasia (BPH) symptoms, he developed an extensive pruritic and purpuric skin rash on his lower legs that subsided after valproic acid discontinuation and therapy with intravenous fluids and oral antihistamines. Therefore, valproic acid was replaced with Pregabalin, which was well tolerated by the patient who recovered quickly. Our clinical experience and the pharmacologic mechanisms underlying the onset of this adverse drug reaction are discussed in detail. Since valproic acid inhibits the uridin-glucuronyl transferase-2B7 (UGT2B7) enzyme that is involved in the metabolism of silodosin, a likely interaction between valproic acid and silodosin elimination pathway has been considered as a possible precipitating factor in our case. The goal of this case report is to draw clinicians’ attention on the significant risk of pharmacokinetic interaction in patients undergoing multiple treatments for different diseases.

Highlights

Valproic Acid (VA) is a simple eight-carbon branched-chain fatty acid belonging to the category of the non-aromatic Antiepileptic Drugs (AED) able to reduce neuronal excitability by different mechanisms of action [1]
We consider our case an example of a non-common drug reaction that has to be considered when poly-therapy is administrated. This case report showed the importance of monitoring side effects, such as itching skin rash, due to VA administration, especially in polytherapy
This is the first case report in which the potential interactions between a widely prescribed Anti-Epileptic Drug, such as Valproic Acid, and a selective α1A-adrenoceptor antagonist not commonly used in psychiatric setting, such as Silodosin, are presented

Summary

Introduction

Valproic Acid (VA) is a simple eight-carbon branched-chain fatty acid belonging to the category of the non-aromatic Antiepileptic Drugs (AED) able to reduce neuronal excitability by different mechanisms of action [1]. When VA is prescribed in poli-pharmacoterapy there is a high chance of pharmacological interactions, mainly due to its ability to inhibit key liver enzymes and to the complexity of its degradation pathways that make interactions with other drugs very likely [8] Many of these interactions are widely known by clinicians and taken into account when a new treatment is added in patients taking VA. Acute cutaneous adverse reactions occur in 3% of hospitalized patients: usually, they rise up within a few days to 4 weeks after the beginning of the therapy and need a discontinuation of the offending drug to be solved. At the end of September 2014, A.C. was admitted to our Department for a depressive relapse including depressed mood, apathy, social withdrawal, insomnia, and deficit of attention He was given pharmacological treatment with: Valproic Acid 300 mg/day; Elopram 40 mg/ml daily intravenous infusion for one week, followed by oral Elopram 40 mg/day; Lorazepam 2.5 mg/day. Two weeks later the admission, the patient experienced a partial remission of his psychiatric symptoms and the skin lesions were completely recovered, with no relapses at one-month follow-up (Figure 3)

Findings

Discussion

Conclusion