Annette Bak, Director at Merck Research Laboratories, spoke at the AAPS annual meeting in San Diego last week about alternatives to parenteral delivery and said that while the US Food and Drug Administration (FDA) recognises 112 different drug delivery routes, transdermal delivery represented a feasible and attractive route for peptides.
While parenteral administration is the most effective route for the delivery of such molecules due to their large molecule size and poor bioavailability, there are issues with safety and compliance that makes an alternative route a worthwhile business prospect, with Bak telling delegates the market for non-parenteral peptide is set to be worth $5bn (€4bn) by 2018, up from $3bn this year.
Bak explained the different delivery routes available for peptides, and while oral is considered the best alternative across a number of criteria – from a patient’s preference standpoint, having an upper dose of 1-2g, and having moderate permeability, among other qualities – transdermal delivery offers passive delivery of small molecules and active delivery of large molecules.
There are two types of transdermal delivery, she explained, overcoming the challenging natural barrier of the skin: Transcellular, involving the transportation of solutes by a cell through a cell, and intercellular – through the lipid matrix occupying the intercellular spaces of the skin cells.
Patches are in use to deliver small molecules but patches are not feasible for peptides due to their large molecular weight, she said. However, microneedles offer “active transdermal delivery” and can deliver most peptides.
Presently there is only one microneedle technology on the market with a drug product – Becton Dickinson’s Soluvia Micro Injection System used by Sanofi’s influenza vaccine Fluzone. However, a number of peptides and microneedle technologies are in trials including Zosano’s solid PTH microneedle patch.
UPDATE - We originally reported the non-parenteral peptide is set to be worth $5bn (€4bn) by 2018, up from $18bn this year. According to Merck these figures are in fact $5bn and $3bn, respectively.