Letrozole 2.5 mg – A quick snapshot
| Topic | Details |
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| What it is | Letrozole is a non‑steroidal aromatase inhibitor that blocks the conversion of androgens to estrogens. It’s sold under the brand name Femara (and other brand names in various countries) and is most commonly prescribed for hormone‑receptor‑positive breast cancer. |
| Typical dose | 2.5 mg once daily (taken orally). This dose is used for adjuvant therapy in post‑menopausal women, for metastatic disease, and for ovarian suppression in certain settings. |
| How it works | By inhibiting aromatase, letrozole reduces circulating estrogen levels, slowing the growth of estrogen‑dependent tumors. |
| Patent landscape |
- Original patents – The primary patents on letrozole (covering the compound itself, its synthesis, and pharmaceutical formulation) were issued to Abbott Laboratories (later Pfizer) in the 1990s (e.g., U.S. Patent 6,048,485, “Letrozole”). Those patents expired in the mid‑2000s (around 2007–2010).
- Generic availability – Because the core patents have expired, generic manufacturers have produced letrozole tablets at a lower cost. Generic versions are widely available in most markets.
- Formulation patents – Some companies may have filed (and some still hold) secondary patents on specific tablet formulations (e.g., sustained‑release, tablet excipients, or particular 2.5 mg dosage forms). These formulation patents are typically shorter in duration and often expire within a few years after the core patent expiry. The most recent publicly listed formulation patents on letrozole expired or are close to expiry in the U.S. (e.g., U.S. Patent 8,892,530 “Letrozole tablets”).
- Patent status in the U.S. – As of the last public update, no active patent that would bar generic manufacture of a 2.5 mg letrozole tablet is in force in the U.S. (the relevant patents have lapsed). However, always check the latest USPTO database if you need the absolute current status.
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Regulatory status | FDA‑approved for the indications above. Over‑the‑counter availability is
not permitted; a prescription is required. |
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Common side effects | Hot flashes, joint pain, fatigue, nausea, bone thinning (osteoporosis risk), and mild GI upset. |
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Notable cautions |
- Not for use in men (unless specifically indicated for a non‑breast‑cancer condition, which is rare).
- May interact with drugs that influence estrogen metabolism (e.g., other aromatase inhibitors, certain anticonvulsants).
- Should be used with bone‑protective measures (e.g., calcium/vitamin D, bisphosphonates) in patients at risk of osteoporosis.
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Key references |
FDA drug label for Femara (2023 revision);
U.S. Patent 6,048,485 (Letrozole);
U.S. Patent 8,892,530 (Letrozole tablets);
EMA approval dossier for letrozole (2002). |
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Bottom line
- The 2.5 mg tablet is a standard, clinically validated dose of letrozole, most commonly used for breast‑cancer treatment.
- The primary patents protecting the drug have long expired, so generics are freely available.
- Any current formulation patents on a specific 2.5 mg tablet are either close to expiration or have already lapsed.
- If you’re considering prescribing or dispensing letrozole, double‑check the local regulatory database or consult a pharmacy‑law resource for the latest patent status in your jurisdiction.
Note: This overview is for informational purposes only. It does not replace professional medical or legal advice.