---
schema_version: "secwatch.filing_event.v1"
accession: "0001297184-26-000013"
form_type: "8-K"
ticker: "AMPH"
cik: "0001297184"
company_name: "Amphastar Pharmaceuticals, Inc."
filed_at: "2026-03-06T23:59:59+00:00"
generated_at: "2026-05-15T18:34:19.821499+00:00"
event_type: "other_material"
sentiment: "neutral"
materiality_score: 0.25
calibrated_materiality_score: 0.25
confidence: "high"
source: SEC EDGAR
---

# Amphastar enters supply agreement with related party Letop, amends contract with Hanxin

## Summary
- Supply agreement with Nanjing Letop (Henry Zhang, son of CEO); no minimum purchase, 5-year term.
- Contract Research Amendment shifts work from AMP-107 to AMP-105; total cost increased by ~$0.6M.
- Both transactions are related-party and approved by Audit Committee; deemed not material.
- Payments under supply agreement will be made in Chinese yuan.

## SEC filing metadata
- accession: 0001297184-26-000013
- form_type: 8-K
- ticker: AMPH
- cik: 0001297184
- company_name: Amphastar Pharmaceuticals, Inc.
- filed_at: 2026-03-06T23:59:59+00:00
- event_type: other_material
- sentiment: neutral
- materiality_score: 0.25
- calibrated_materiality_score: 0.25
- confidence: high
- sec_items: 1.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1297184/000129718426000013/0001297184-26-000013-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1297184/000129718426000013/amph-20260303x8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001297184-26-000013
- JSON: https://secwatch.observer/filing/0001297184-26-000013.json
- Plain text: https://secwatch.observer/filing/0001297184-26-000013.txt

## Key facts
- Material Agreements
  Amphastar Pharmaceuticals, Inc. entered into Supply Agreement with Nanjing Letop Biotechnology Co., Ltd. (effective 2026-03-03).
  - Action: entry
  - Agreement: supply
  - Counterparty: Nanjing Letop Biotechnology Co., Ltd.
  - Effective: 2026-03-03
  source text: On March 3, 2026, (the “Effective Date”), Amphastar Nanjing Pharmaceuticals, Inc. (“ANP”), the Chinese subsidiary of Amphastar Pharmaceuticals, Inc. (“Amphastar” or, the “Company”), entered into a supply agreement (the “Supply Agreement”) with Nanjing Letop Biotechnology Co., Ltd. (“Letop”).
  evidence_url: https://www.sec.gov/Archives/edgar/data/1297184/000129718426000013/0001297184-26-000013-index.htm
- Material Agreements
  Amphastar Pharmaceuticals, Inc. amended Contract Research Amendment with Nanjing Hanxin Pharmaceutical Technology Co., Ltd. valued at approximately $0.6 million (effective 2026-03-03).
  - Action: amendment
  - Agreement: collaboration
  - Counterparty: Nanjing Hanxin Pharmaceutical Technology Co., Ltd.
  - Value: approximately $0.6 million
  - Effective: 2026-03-03
  source text: On March 3, 2026 (the “Effective Date”), Amphastar Pharmaceuticals, Inc (“Amphastar” or, the “Company”) and Nanjing Hanxin Pharmaceutical Technology Co., Ltd. (“Hanxin”) entered into an amendment (the “Contract Research Amendment”) to the Contract Research Agreement (the “Contract Research Agreement”), originally entered into on September 15, 2025, as previously reported by the Company on a Current Report on Form 8-K filed on September 18, 2025.
  evidence_url: https://www.sec.gov/Archives/edgar/data/1297184/000129718426000013/0001297184-26-000013-index.htm

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.