Employee Stock Purchase Plan	12 Months Ended
Dec. 31, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Employee Stock Purchase Plan	13. Employee Stock Purchase Plan On August 17, 2021, a special meeting of the Company’s stockholders was held to approve the Merger and related matters which included, among others, an employee stock purchase plan (“Special Meeting”). At the Special Meeting, the Company’s stockholders considered and approved the Company’s 2021 Employee Stock Purchase Plan (the “2021 ESPP”). Upon approval of the 2021 ESPP by the stockholders, Aerpio’s Amended and Restated 2017 Employee Stock Purchase Plan terminated. An aggregate of 310,617 shares of common stock have been reserved and are available for issuance under the 2021 ESPP. The number of shares of common stock available for issuance under the 2021 ESPP will be increased on the first day of each fiscal year beginning with the 2022 fiscal year in an amount equal to the least of (i) 310,617 shares of common stock, (ii) one percent (1%) of the outstanding shares of all classes of common stock on the last day of the immediately preceding fiscal year, or (iii) an amount to be determined by the Board or its designated committee no later than the last day of the immediately preceding fiscal year. On January 1, 2022, 208,946 shares of common stock were added to the 2021 ESPP. Shares of common stock issuable under the 2021 ESPP will be authorized, but unissued, or reacquired shares of common stock. If the Company’s capital structure changes because of a stock dividend, stock split or similar event, the number of shares that can be issued under the 2021 ESPP will be appropriately adjusted. No shares were issued under the 2021 ESPP as of December 31, 2021.

Employee Stock Purchase Plan

12 Months Ended

Dec. 31, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

13. Employee Stock Purchase Plan

On August 17, 2021, a special meeting of the Company’s stockholders was held to approve the Merger and related matters which included, among others, an employee stock purchase plan (“Special Meeting”). At the Special Meeting, the Company’s stockholders considered and approved the Company’s 2021 Employee Stock Purchase Plan (the “2021 ESPP”). Upon approval of the 2021 ESPP by the stockholders, Aerpio’s Amended and Restated 2017 Employee Stock Purchase Plan terminated. An aggregate of 310,617 shares of common stock have been reserved and are available for issuance under the 2021 ESPP. The number of shares of common stock available for issuance under the 2021 ESPP will be increased on the first day of each fiscal year beginning with the 2022 fiscal year in an amount equal to the least of (i) 310,617 shares of common stock, (ii) one percent (1%) of the outstanding shares of all classes of common stock on the last day of the immediately preceding fiscal year, or (iii) an amount to be determined by the Board or its designated committee no later than the last day of the immediately preceding fiscal year. On January 1, 2022, 208,946 shares of common stock were added to the 2021 ESPP. Shares of common stock issuable under the 2021 ESPP will be authorized, but unissued, or reacquired shares of common stock. If the Company’s capital structure changes because of a stock dividend, stock split or similar event, the number of shares that can be issued under the 2021 ESPP will be appropriately adjusted. No shares were issued under the 2021 ESPP as of December 31, 2021.