Summary of Significant Accounting Policies | 2. Summary of Significant Accounting Policies Basis of Presentation and Consolidation The accompanying audited consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles, or U.S. GAAP. The consolidated financial statements include the operations of Impel Neuropharma, Inc., and its wholly owned Australian subsidiary. All intercompany balances and transactions have been eliminated upon consolidation. Reclassifications We have reclassified prior period financial statements to conform to the current period presentation. We reclassified certain amounts previously recorded as general and administrative expense to res earch and development expense. The reclassification had no impact on total operating costs, loss from operations, net loss, stockholders’ equity (deficit) or cash flows. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, management evaluates such estimates and assumptions for continued reasonableness. In particular, management makes estimates with respect to revenue recognition, inventory valuation, the fair values of common stock (prior to the Company's IPO), common stock and redeemable convertible preferred stock warrant liabilities, stock-based compensation expense, convertible debt and income taxes. Appropriate adjustments, if any, to the estimates used are made prospectively based upon such periodic evaluation. Actual results could differ from those estimates. Segments The Company’s chief operating decision maker is its Chief Executive Officer. The Chief Executive Officer reviews financial information on an aggregate basis for the purposes of evaluating financial performance and allocating the Company’s resources. Accordingly, the Company has determined that it operates in one segment. Substantially all of the Company’s assets are located in the U.S. Cash The Company considers all highly liquid investments with original maturities of three months or less from the date of purchase to be cash equivalents. At December 31, 2021 and 2020, cash consisted of cash in bank deposits held at financial institutions. Accounts Receivable, net The Company’s trade accounts receivable consists of amounts due from specialty pharmacies and specialty distributors in the U.S. net of distribution service fees, prompt pay discounts and other adjustments. The Company's contracts with customers have standard payment terms that generally require payment within 45 days . The Company analyzes accounts that are past due for collectability, and periodically evaluates the creditworthiness of its customers. As of December 31, 2021, we determined an allowance for doubtful accounts was not req uired based upon our review of contractual payment terms and individual customer circumstances. The Company had no accounts receivable related to product sales in 2020. Revenue Recognition The Company recognizes revenue in accordance with ASC Topic 606, Revenue from Contracts with Customers (“ASC 606”). Under ASC 606, an entity recognizes revenue when its customer obtains control of promised goods or services in an amount that reflects the consideration which the entity expects to receive in exchange for those goods or services. Product Revenue, Net Subsequent to its regulatory approval in the U.S. in September 2021, the Company began to sell Trudhesa in the U.S. The product is distributed through an exclusive third-party logistics, or 3PL, distribution agent that does not take title to the product. The 3PL distributes Trudhesa to the Company's customers, a specialty pharmacy and a specialty distributor (collectively referred to as "customers"), who then distribute the product to health care providers and patients. In our exclusive distribution agreement with the 3PL company, the Company acts as principal because we retain control of the product. Revenue from product sales is recognized when the customer obtains control of our product, which occurs upon transfer of title to the customer. We classify payments to customers or other parties in the distribution channel for services that are distinct and priced at fair value as selling, general and administrative expenses in our consolidated statements of operations. Payments to customers or other parties in the distribution channel that do not meet those criteria are classified as a reduction of revenue, as discussed further below. Taxes collected from the customer relating to product sales and remitted to governmental authorities are excluded from revenue. Because our payment terms are generally forty-five days, we conclude there is not a significant financing component because the period between the transfer of a promised good or service to the customer and when the customer pays for that good or service will be one year or less. The Company expenses incremental costs of obtaining a contract as and when incurred since the expected amortization period of the asset that we would have recognized is one year or l ess. Reserves for Variable Consideration Revenues from product sales are recorded at the net sales price, or the transaction price, which includes estimates of variable consideration for which reserves are established and which result from discounts, returns, co-pay assistance, chargebacks, rebates and other allowances that are offered within contracts between us and our customer, health care providers and other indirect customers relating to the sale of Trudhesa. These reserves are based on the amounts earned or to be claimed on the related sales and are classified as reductions of accounts receivable or a current liability. Where appropriate, these estimates take into consideration a range of possible outcomes that are probability-weighted for relevant factors such as our historical experience, current contractual and statutory requirements, specific known market events and trends, industry data and forecasted customer buying and payment patterns. Overall, these reserves reflect our best estimates of the amount of consideration to which we are entitled based on the terms of the contract. The amount of variable consideration that is included in the transaction price may be constrained and is included in the net sales price only to the extent that it is considered probable that a significant reversal in the amount of the cumulative revenue recognized will not occur in a future period. Actual amounts of consideration ultimately received may differ from our estimates. If actual results in the future vary from our estimates, we will adjust these estimates, which would affect net product revenue and earnings in the period such variances become known. The following are the components of variable consideration related to product revenue: Product Returns : Our customer has limited return rights related to the product’s damage or defect. The Company estimates the amount of product sales that may be returned and records the estimate as a reduction of revenue and a refund liability in the period the related product revenue is recognized. Based on the distribution model for Trudhesa and the price of Trudhesa, the Company believes there will be minimal returns. Other incentives : Other incentives include co-payment assistance the Company provides to patients with commercial insurance that have coverage and reside in states that allow co-payment assistance. The calculation of the accrual for co-pay assistance is based on an estimate of claims and the cost per claim that we expect to receive associated with product that has been recognized as revenue. The estimate is recorded as a reduction of revenue in the same period the related revenue is recognized. Managed care rebates : The Company is subject to rebates with certain commercial payers in the future. We record these rebates as an accrual on our consolidated balance sheet in the same period we recognize the related revenue. We estimate our managed care rebates based on our estimated payer mix and the applicable contractual rebate rate. Chargebacks : The Company estimates obligations resulting from contractual commitments with the government and other entities to sell products to qualified healthcare providers and patients at prices lower than the list prices charged to our customer. The government and other entities charge us for the difference between what they pay for the product and the selling price to our customer. The Company records reserves for these chargebacks related to product sold to our customer during the reporting period, as well as our estimate of product that remains in the distribution channel at the end of the reporting period that we expect will be sold to qualified healthcare providers and patients in future periods. As of December 31, 2021, Impel did not enter into any contracts with government entities and other entities that are eligible for chargebacks. Government rebates : The Company is subject to discount obligations under government programs, including Medicaid programs, Medicare and Tricare in the U.S. We estimate Medicaid, Medicare and Tricare rebates based upon a range of possible outcomes that are probability-weighted for the estimated payer mix. These reserves are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a liability that is included in accrued expenses on our consolidated balance sheet. For Medicare, we also estimate the number of patients in the prescription drug coverage gap for whom we will owe an additional liability under the Medicare Part D program. On a quarterly basis, we update our estimates and record any adjustments in the period that we identify the adjustments. Inventory Prior to receiving approval from the FDA in September 2021 to sell Trudhesa in the U.S., the Company expensed all costs incurred related to the manufacture of Trudhesa as research and development expense because of the inherent risks associated with the development of a drug candidate, the uncertainty about the regulatory approval process and the lack of history for the Company of regulatory approval of drug candidates. Subsequent to receiving FDA approval in September 2021, the Company began to capitalize inventory related costs that were incurred subsequent to FDA approval. T he Company values its inventories at the lower-of-cost or net realizable value and determines the cost of its inventories, which includes costs related to products held for sale in the ordinary course of business, products in process of production for such sale and items to be currently consumed in the production of goods to be available for sale, on a first-in, first-out (FIFO) basis. Due to the nature of the Company’s supply chain process, inventory that is owned by the Company, is physically stored at third-party warehouses, logistics providers and contract manufacturers. The Company performs an assessment of the recoverability of capitalized inventory during each reporting period, and writes down any excess and obsolete inventories to their net realizable value in the period in which the impairment is first identified. If they occur, such impairment charges are recorded as a component of cost of goods sold in the consolidated statements of operations and comprehensive loss. Concentration of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash. The Company’s cash is deposited with high credit quality financial institutions. At times such deposits may be in excess of the Federal Depository Insurance Corporation insured limits. The Company has exposure to credit risk in accounts receivable from sales of product. As of December 31, 2021, two customers accounted for 100 % of the accounts receivable balance and revenues, with each of these individual customers ranging fro m 46 % to 54 % of the accounts receivable balance. Property and Equipment, Net Property and equipment are stated at cost, net of accumulated depreciation and amortization. Depreciation is computed using the straight-line method over the estimated useful lives of the depreciable assets, ranging from three to four years. Property and equipment are primarily comprised of laboratory and platform equipment used to support manufacturing and research and development activities. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is reflected in the statement of operations in the year of disposition. Additions and improvements that increase the value or extend the life of an asset are capitalized. Repairs and maintenance costs are expensed as incurred. Leasehold improvements are amortized over the remaining term of the lease or the asset’s useful life, whichever is shorter. Impairment of Long-Lived Assets The Company reviews long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset or asset group may not be recoverable. The recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset or asset group to the estimated undiscounted future cash flows expected to be generated by the asset or asset group. If the carrying amount of an asset or asset group exceeds its estimated undiscounted future cash flows, an impairment charge is recognized as the amount by which the carrying amount of the asset exceeds the estimated discounted future cash flows of the asset or asset group. There have been no such impairments of long-lived assets for any of the periods presented. Fair Value Measurement Assets and liabilities recorded at fair value on a recurring basis in the balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows: Level 1—Observable inputs such as unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date; Level 2—Inputs (other than quoted prices included in Level 1) are either directly or indirectly observable for the asset or liability. These include quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active; Level 3— Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The carrying amounts reflected in the accompanying consolidated balance sheets for cash, other current assets, accounts payable, and accrued liabilities approximate their fair values, due to their short-term nature. The C ompany estimated the fair value of long-term debt as of December 31, 2021 was $ 32.5 M and was based on the company’s credit rating and comparison with current prevailing market rates for loans of similar risks and maturities. Leases The Company leases office space and laboratory facilities under non-cancelable operating leases. The Company recognizes rent expense on a straight-line basis over the noncancelable lease period and records the difference between cash rent payments and the recognition of rent expense as a deferred rent liability. When leases contain escalation clauses, rent abatements and landlord or tenant incentives or allowances, these terms are applied in the determination of straight-line rent expense over the lease period. Convertible Notes In March 2021, the Company issued convertible promissory notes to various investors for an aggregate amount of $ 7.5 million. As permitted under Accounting Standards Codification ("ASC") 825, Financial Instruments ("ASC 825"), the Company elected the fair value option for recognition of the convertible notes. The Company elected the fair value option to allow the Company to eliminate the burden of complying with the requirements for derivative accounting. Under the fair value option, the convertible notes were remeasured at fair value in each reporting period until their conversion in April 2021, with changes in the fair value recognized in the Company’s consolidated statement of operations as other (expense) income, net. Accrued interest on the convertible notes is recorded in other (expense), net. The notes were automatically converted into shares of the Company’s common stock upon the closing of the IPO in April 2021. C ost of Goods Sold Cost of goods sol d consists primarily of third-party manufacturing, distribution, and overhead costs associated with Trudhesa. A portion of the costs of producing Trudhesa sold to date was expensed as research and development prior to the FDA approval of Trudhesa and, therefore, it is not reflected in the cost of goods sold. Cost of goods sold for the year ended December 31, 2021, included a charge of $ 0.2 million related to the write down of inventory to net realizable value in the consolidated statements of operations and comprehensive loss. Research and Development Expense Research and development costs are expensed as incurred and consist primarily of salaries, benefits and other staff-related costs, including associated stock-based compensation, laboratory supplies, nonclinical and clinical studies and trials and related clinical manufacturing costs, costs related to manufacturing preparation, fees paid to other entities that conduct certain research and development activities on the Company’s behalf. Non-refundable advance payments for goods or services that will be used or rendered for future research and development activities are deferred and capitalized as prepaid expenses until the related goods are delivered or services are performed. Such payments are evaluated for current or long-term classification based on when such services are expected to be received. The Company considers regulatory approval of product candidates to be uncertain, and product manufactured prior to regulatory approval may not be sold unless regulatory approval is obtained. The Company expenses manufacturing costs as incurred to research and development expense for product candidates prior to regulatory approval. If, and when, regulatory approval of a product is obtained, the Company begins capitalizing manufacturing costs related to the approved product into inventory. Selling, General and Administrative Expense Selling, general and administrative expenses are primarily comprised of compensation and benefits associated with sales and marketing, finance, human resources, legal, information technology and other administrative personnel, outside marketing, advertising and legal expenses and other general and administrative costs. The Company expenses the cost of advertising, including promotional expenses, as incurred. Advertising expenses were $ 10.6 million for the year ended December 31, 2021. The Company did no t incur any advertising expenses for the year ended December 31, 2020. Advance Payments and Accruals for Research and Development Services As part of the process of preparing its consolidated financial statements, the Company is required to estimate its expenses resulting from its obligation under contracts with vendors and consultants and clinical site agreements in connection with its research and development efforts. The financial terms of these contracts are subject to negotiations which vary contract to contract and may result in payment flows that do not match the periods over which materials or services are provided to the Company under such contracts. The Company’s objective is to reflect the appropriate research and development expenses in its consolidated financial statements by matching those expenses with the period in which services and efforts are expended. The Company accounts for these expenses according to the progress of its research and development efforts. The Company determines advance payments for research and development services and accrual estimates through discussion with applicable personnel and outside service providers as to the progress of clinical trials, or other services completed. The Company adjusts its rate of research and development expense recognition if actual results differ from its estimates. The Company makes estimates of its advance payments and accrued expenses as of each balance sheet date in its consolidated financial statements based on facts and circumstances known at that time. Although the Company does not expect its estimates to be materially different from amounts actually incurred, its understanding of status and timing of services performed relative to the actual status and timing of services performed may vary and may result in the Company reporting amounts that are too high or too low for any particular period. Through December 31, 2021, there had been no material adjustments to the Company’s prior period estimates of advance payments and accruals for research and development expenses. The Company’s research and development advance payments and accruals are dependent upon the timely and accurate reporting of contract research organizations and other third-party vendors. Warrant Liabilities The Company determines the accounting classification of warrants that are issued, as either liability or equity, by first assessing whether the warrants meet liability classification in accordance with ASC 480-10 , Accounting for Certain Financial Instruments with Characteristics of both Liabilities and Equity, ("ASC 480-10"), and then in accordance with ASC 815-40, Derivatives and Hedging -- Contracts in Entity's Own Equity ("ASC 815-40"). Under ASC 480-10, warrants are considered liability classified if the warrants are mandatorily redeemable, obligate the issuer to settle the warrants or the underlying shares by paying cash or other assets, or must or may require settlement by issuing variable number of shares. If the warrants do not meet liability classification under ASC 480-10, the Company assesses the requirements under ASC 815-40, which states that contracts that require or may require the issuer to settle the contract for cash are liabilities recorded at fair value, irrespective of the likelihood of the transaction occurring that triggers the net cash settlement feature. If the warrants do not require liability classification under ASC 815-40, in order to conclude equity classification, the Company assesses whether the warrants are indexed to its common stock and whether the warrants are classified as equity under ASC 815-40 or other applicable GAAP. After all relevant assessments are made, the Company concludes whether the warrants are classified as liability or equity. Liability classified warrants are required to be accounted for at fair value both on the date of issuance and on subsequent accounting period ending dates, with all changes in fair value after the issuance date recorded as a component of other (expense) income, net in the accompanying consolidated statements of operations. Equity classified warrants are accounted for at fair value on the issuance date with no changes in fair value recognized after the issuance date. See Note 6 and 7 for additional details. Stock-Based Compensation The Company recognizes stock-based compensation expense for stock options and restricted stock unit awards on a straight-line basis over the requisite service period. The Company’s stock-based compensation costs for stock options are based upon the grant date fair value of options estimated using the Black-Scholes-Merton option pricing model. This model utilizes as inputs the estimated fair value of the underlying common stock at the measurement date, the estimated term of the stock options (weighted-average period of time that the options granted are expected to be outstanding), risk-free interest rates, expected dividends, and the expected volatility of the Company’s common stock. The Company has elected to recognize forfeitures of share-based payment awards as they occur. In determining the fair value of the stock options granted, the Company uses the Black-Scholes option-pricing model and assumptions discussed below. Each of these inputs is subjective. Fair Value of Common Stock— Prior to the IPO, given the absence of a public trading market, the Company’s board of directors with input from management considered numerous objective and subjective factors to determine the fair value of common stock. The factors included, but were not limited to: (1) third-party valuations of the Company’s common stock; (2) the Company’s stage of development; (3) the status of research and development efforts; (4) the rights, preferences and privileges of the Company’s preferred stock relative to those of the Company’s common stock; (5) the Company’s operating results and financial condition, including the Company’s levels of available capital resources; and (6) equity market conditions affecting comparable public companies; (7) general U.S. market conditions; and (8) the lack of marketability of the Company’s common stock. Following the IPO, as a public trading market for the Company’s common stock has been established, the fair value of the common stock is determined based on the quoted market price of the common stock on the date of grant. Expected Term —The Company’s expected term represents the period that the Company’s stock-based awards are expected to be outstanding. The Company used the simplified method (based on the mid-point between the vesting date and the end of the contractual term) to determine the expected term. Expected Volatility —Since the Company recently completed its IPO and does not have substantial trading history for its common stock, the expected volatility was estimated based on the average historical volatilities for comparable publicly traded pharmaceutical companies over a period equal to the expected term of the stock option grants. The comparable companies were chosen based on their similar size, stage in the life cycle and area of specialty. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available. Risk-Free Interest Rate —The risk-free interest rate is based on the U.S. Treasury zero coupon issues in effect at the time of grant for periods corresponding with the expected term of option. Expected Dividend —The Company has never paid dividends on its common stock and has no plans to pay dividends on its common stock. Therefore, the Company used an expected dividend yield of zero. The Company recognizes stock-based compensation expense for stock options granted to non-employees based on the estimated fair value of the award as it is more readily measurable than the fair value of the services received. Restricted stock units and performance stock units have a grant-date fair value equal to the fair market value of the underlying stock on the grant date. Compensation expense for performance stocks units with performance metrics is calculated based upon expected achievement of the metrics specified in the grant, or when a grant contains a market condition, the grant date fair value using a Monte Carlo simulation. Income Taxes Income taxes are accounted for using the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts or existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using the enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period of enactment. The Company records a valuation allowance to reduce deferred tax assets to an amount for which realization is more likely than not. The Company recognizes the tax benefit from an uncertain tax position if it is more likely than not that the tax position will be sustained upon examination by the tax authorities, based on the merits of the position. The Company does not believe any uncertain tax positions currently pending will have a material adverse effect on its consolidated financial statements nor does the Company expect any material change in its position in the next 12 months. The Company’s policy is to recognize interest and penalties related to the underpayment of income taxes as a component of income tax expense or benefit. To date, there have been no interest or penalties charged in relation to the unrecognized tax benefits. Net Loss Per Share Attributable to Common Stockholders Basic net loss per share attributable to common stockholders is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding for the period, without consideration of potentially dilutive securities. Diluted net loss per share attributable to common stockholders is the same as basic net loss per share attributable to common stockholders since the effect of potentially dilutive securities is anti-dilutive given the net loss of the Company. Comprehensive Loss Comprehensive loss represents the change in the Company’s stockholders’ equity (deficit) from all sources other than investments by or distributions to stockholders. The Company has no items of other comprehensive loss; as such, net loss equals comprehensive loss. Recent Accounting Pronouncements In February 2016, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, No. 2016-02, Leases , or Topic 842, which supersedes the guidance in former ASC 840, Leases . This standard requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase by the lessee. This classification will determine whether lease expense is recognized based on an effective interest method or on a straight-line basis over the term of the lease. A lessee is also required to record a right-of-use asset and a lease liability for all leases with a term of greater than 12 months regardless of their classification. Leases with a term of 12 months or less may be accounted for as a period cost. In May 2020, the FASB issued ASU No. 2020-05, Revenue from Contracts with Customers (Topic 606) and Leases (Topic 842): Effective Dates for Certain Entities, which deferred the effective dates for non-public entities. Therefore, this standard is effective for annual reporting periods, and interim periods within those years, for public entities beginning after December 15, 2018 and for private entities beginning after December 15, 2021. As an Emerging Growth Company, we have elected to follow the private company adoption timeline for ASC 842. Originally, a modified retrospective transition approach was required for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. In July 2018, the FASB issued guidance to permit an alternative transition method for Topic 842, which allows transition to the new lease standard by recognizing a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. Entities may elect to apply either approach. There are also a number o |