The following table sets forth the major categories of intangible assets and the weighted-average remaining useful lives for those assets that are not already fully amortized or impaired:


	March 31, 2024
(in thousands, except for in years)	Remaining Useful Lives (in years)	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
Distribution rights	4.0	$	32,334	$	(23,609)	$	8,725
Total intangible assets		$	32,334	$	(23,609)	$	8,725


	December 31, 2023
(in thousands, except for in years)	Weighted-average Remaining Useful Lives (in years)	Gross Carrying Amount		Accumulated Amortization		Accumulated Impairment		Net Carrying Amount
Distribution rights	4.3	$	32,334	$	(23,064)	$	—	$	9,270
Internally developed technology(1)	1.5	8,918		(4,408)		(3,972)		538		(1)
Acquired developed technology	0.0	16,200		(6,525)		(9,675)		—
Customer relationships	0.0	10,300		(7,940)		(2,360)		—
Total intangible assets		$	67,752	$	(41,937)	$	(16,007)	$	9,808

(1)During the three months ended March 31, 2024, we reclassified the $0.5 million net carrying amount of internally developed technology to “Non-current assets of discontinued operations” in connection with the discontinued operations presentation.

Amortization expense of the intangible assets in the table above were recorded on the condensed consolidated statements of operations and comprehensive loss based on the function of the associated asset. The detail breakdown of the amortization expenses on the condensed consolidated statements of operations and comprehensive loss were summarized as below:


	Three Months Ended March 31, 2024
(in thousands)	Amortization of Intangible Assets (1)		Classified as Discontinued Operations (2)		Classified as Continuing Operations
Amortization	$	545	$	—	$	545
Selling, general and administrative	528		(528)		—
Research and development	10		(10)		—
Total amortization expense	$	1,083	$	(538)	$	545


	Three Months Ended March 31, 2023
(in thousands)	Amortization of Intangible Assets (1)		Classified as Discontinued Operations (2)		Classified as Continuing Operations
Amortization	$	2,004	$	(1,459)	$	545
Selling, general and administrative	1,737		(644)		1,093
Research and development	261		—		261
Total amortization expense	$	4,002	$	(2,103)	$	1,899

(1)Amount represents the amortization expense before the impact of reclassification for the discontinued operation presentation in the condensed consolidated statements of operations and comprehensive loss.

(2)Amount represents the reclassification for the current and prior periods for the discontinued operation presentation in the condensed consolidated statements of operations and comprehensive loss.

Based on the amount of intangible assets as of March 31, 2024, the expected amortization expense for each of the next five fiscal years was as follows:


Year Ending December 31,	(in thousands)
2024 remaining nine months	$	1,637
2025	2,181
2026	2,181
2027	2,181
2028	545
2029 and thereafter	—
Total	$	8,725