Pirfenidone

Absorption

After a single oral-dose administration of 801 mg pirfenidone (as three 267 mg capsules), the Tmax ranged from 30 minutes to four hours. Food affects the absorption and safety profile of pirfenidone: in one study, food increased Tmax; decreased Cmax and AUC by 49% and 16%, respectively; and decreased the incidence of pirfenidone-induced adverse reactions.

Toxicity

In rats, the oral and intraperitoneal LD50 are 1295 mg/kg and 430 mg/kg, respectively.
There is limited clinical experience with overdosage of pirfenidone. A maximum tolerated pirfenidone dose of 4005 mg per day was tolerated when the drug was administered as five 267 mg capsules three times daily to healthy adult volunteers over a 12-day dose escalation. Overdosage should be managed with supportive and symptomatic care, including monitoring of vital signs and observation of the clinical status of the patient.

Description

Until recently, IPF therapy consisted of a combination of corticosteroids and immunosuppressive agents (azathioprine and cyclophosphamide) to target the inflammation that was believed to be the pathogenic stimulus.Since IPF is now considered to be predominantly a disorder of fibroproliferation, agents that intervene in fibrogenesis have moved to the forefront of treatment options. With demonstrated efficacy in a bleomycin-induced lung fibrosis animal model, pirfenidone has been developed and launched as an approved therapy for IPF. Its antifibrotic activity is derived from the inhibition of p38 MAP kinase that is upstream of transforming growth factor-β (TGF-β), a cytokine implicated in the stimulation of collagen synthesis and the inhibition of its degradation. Pirfenidone also inhibits the expression of TNF-α, IL-1, and ICAM-1, so it possesses the dual benefit of an anti-inflammatory and antifibrotic agent. This relatively simplistic drug is constructed by the copper-catalyzed reaction of 5-methyl-2(1H)-pyridinone with bromo- or chlorobenzene. .

Description

Idiopathic pulmonary fibrosis (IPF) is a fatal lung disease of unknown origin. Drug companies have sought a treatment for IPF for many years. Several concentrated on developing pirfenidone, including InterMune of Brisbane, CA; Shionogi of Osaka, Japan; and GNI Group of Tokyo. The drug was first approved for treatment in China in 2008, followed by approvals in India in 2010, Europe in 2011, Canada in 2012, and the United States and Mexico in 2014.
In August 2014, before pirfenidone was approved by the US Food and Drug Administration,?Roche (Basel, Switzerland) paid US$8.3 billion to acquire InterMune. The product is expected to add US$1.6 billion to Roche’s annual sales by 2020.

The Uses of Pirfenidone

Pirfenidone is in a group of medicines called antifibrotic agents. Pirfenidone has demonstrated activity in multiple fibrotic conditions, including those of the lung, kidney and liver. It affects your body’s immune system and reduces the amount of fibrosis (scarring) in the lungs. Pirfenidone is one of two medicines that are approved in Canada to treat Idiopathic Pulmonary Fibrosis (IPF). Another name for this medicine is Esbriet.

Background

Pirfenidone is a synthetic pyridone drug. It is an antifibrotic agent with anti-inflammatory and antioxidant properties that is used to treat idiopathic pulmonary fibrosis (IPF), which is a chronic, progressive form of interstitial pneumonia. While its mechanism of action is not yet fully understood, pirfenidone is proposed to primarily regulate tumor necrosis factor (TNF) pathways and modulate cellular oxidation. The FDA first approved pirfenidone alongside nintedanib as one of the first drugs to treat IPF.

Indications

Pirfenidone is indicated for the treatment of idiopathic pulmonary fibrosis (IPF). In Canada and Europe, it is approved in adults only.

What are the applications of Application

Pirfenidone is an antifibrotic and antioxidant small molecule

Pharmacokinetics

Pirfenidone is a novel agent with anti-inflammatory, antioxidant, and antifibrotic properties. It may improve lung function and reduce the number of acute exacerbations in patients with idiopathic pulmonary fibrosis (IPF).

Metabolism

According to in vitro studies, about 70-80% of pirfenidone metabolism is mediated by CYP1A2, as well as some minor contributions from CYP2C9, 2C19, 2D6, and 2E1. Four metabolites have been detected after oral administration of pirfenidone. In vitro data suggest that metabolites are not expected to be pharmacologically active at observed metabolite concentrations. The exact metabolic pathways of pirfenidone have not been fully characterized; however, one of the pathways involve CYP1A2-mediated 5-hydroxylation and subsequent oxidation to form 5-carboxy pirfenidone. In humans, only pirfenidone and 5-carboxy pirfenidone are present in plasma in significant quantities. The mean metabolite-to-parent ratio ranged from approximately 0.6 to 0.7.