Generic entry timeline

Cytoxan (Lyophilized) generics — when can they launch?

Cytoxan (Lyophilized) (cyclophosphamide) · Baxter · 15 active US patents · 0 expired

Earliest patent expiry

2035-06-26

9 years remaining

Full patent estate to

2036-02-15

complete protection through 2036

FDA approval

1959

Baxter

Where Cytoxan (Lyophilized) sits in the generic timeline

Long-dated protection: earliest active US patent for Cytoxan (Lyophilized) extends to 2035 (~9 years out). Generic competition is at least 4 years away. Lifecycle moves (new formulations, label extensions, combination filings) typically execute 18-36 months ahead of cliff.

Under US Hatch-Waxman, a generic enters via an ANDA (Abbreviated New Drug Application) and may file with one of four Paragraph IV certifications attacking the brand's listed patents. If the brand sues within 45 days, a 30-month FDA approval stay is triggered. First Para IV filer typically gets 180-day market exclusivity.

Patent estate by type — active patents

Method-of-use patents only carve out specific indications; generics can launch with a "skinny label" omitting those uses. Composition-of-matter patents block the molecule itself.

Formulation — 15 patents

Sample patent estate

Showing 6 of 15 active US patents. View full estate on the Cytoxan (Lyophilized) drug page →

US9662342 Formulation · expires 2035-06-26

This patent protects formulations of cyclophosphamide liquid concentrate that maintain high levels of cyclophosphamide content after storage for 18 or 24 months at 5°C.

USPTO title: Formulations of cyclophosphamide liquid concentrate
US9662342 Formulation · expires 2035-06-26

This patent protects formulations of cyclophosphamide liquid concentrate that maintain high levels of cyclophosphamide content after storage for 18 or 24 months at 5°C.

USPTO title: Formulations of cyclophosphamide liquid concentrate
US9662342 Formulation · expires 2035-06-26

This patent protects formulations of cyclophosphamide liquid concentrate that maintain high levels of cyclophosphamide content after storage for 18 or 24 months at 5°C.

USPTO title: Formulations of cyclophosphamide liquid concentrate
US10849916 Formulation · expires 2035-07-13

This patent protects stable liquid formulations of the cancer drug cyclophosphamide, including certain impurities, for parenteral administration.

USPTO title: Stable liquid formulations of cyclophosphamide and its impurities
US10849916 Formulation · expires 2035-07-13

This patent protects stable liquid formulations of the cancer drug cyclophosphamide, including certain impurities, for parenteral administration.

USPTO title: Stable liquid formulations of cyclophosphamide and its impurities
US10849916 Formulation · expires 2035-07-13

This patent protects stable liquid formulations of the cancer drug cyclophosphamide, including certain impurities, for parenteral administration.

USPTO title: Stable liquid formulations of cyclophosphamide and its impurities

Sources

FDA Orange Book — patents listed against Cytoxan (Lyophilized) (NDA filed 1959)
Cytoxan (Lyophilized) drug profile — full patent estate, indications, clinical trials, pricing
Baxter patent portfolio
Patent cliff 2035 — every drug losing US exclusivity that year

Patent term extensions (PTR, pediatric exclusivity), Hatch-Waxman 30-month stays, and FDA regulatory exclusivity (NCE/ODE/PED) may shift the effective generic entry date. Not legal advice.

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