4. INVENTORY

The following table presents our inventory of ONPATTRO at September 30, 2018 and December 31, 2017, in thousands:

	At September 30, 2018		At December 31, 2017
Raw materials	$	4,789	$	—
Work in process		6,213		—
Finished goods		79		—
Total inventory	$	11,081	$	—

At September 30, 2018, all of our inventory was related to ONPATTRO, which was approved by the FDA and the EC on August 10, 2018 and August 30, 2018, respectively. In the third quarter of 2018, we began to capitalize inventory costs for ONPATTRO as a result of the approval of ONPATTRO by the FDA and commercial sales forecasts for ONPATTRO. Prior to the third quarter of 2018, we recorded the costs associated with ONPATTRO raw materials, work in process and finished goods as research and development expenses on our condensed consolidated statements of comprehensive loss. At September 30, 2018, we had $21.3 million of this zero-cost ONPATTRO inventory. At September 30, 2018, we have determined a reserve related to ONPATTRO inventory is not required based on our evaluation of factors including commercial sales forecasts for ONPATTRO and the shelf life of ONPATTRO inventory.