1. Clinical Overview
Doxorubicin (Liposomal) is a pegylated, liposome-encapsulated formulation of the anthracycline antibiotic doxorubicin. It is designed to enhance drug delivery to tumor sites while reducing systemic exposure and certain toxicities, most notably cardiotoxicity and myelosuppression, compared to conventional doxorubicin. The liposomal encapsulation alters pharmacokinetics, leading to prolonged circulation time and preferential accumulation in tumor tissue via the Enhanced Permeability and Retention (EPR) effect. It is a critical component of chemotherapy regimens for specific cancers in India.
| Onset | Duration | Bioavailability |
|---|---|---|
| Cytotoxic effects begin upon cellular uptake and DNA intercalation, but clinical tumor response typically takes several weeks to assess after multiple cycles. | The cytotoxic effect is prolonged due to sustained release from liposomes. Pharmacodynamic effects on blood counts (nadir) are typically observed 7-14 days post-infusion. | Not applicable; administered exclusively via intravenous infusion. 100% systemic bioavailability via this route. |
2. Mechanism of Action
The liposomal formulation delivers doxorubicin to tumor sites. Once internalized by tumor cells and doxorubicin is released, it intercalates between DNA base pairs, causing uncoiling of the DNA helix. This inhibits the progression of the enzyme topoisomerase II, which is essential for DNA replication and repair. The stabilization of the topoisomerase II-DNA complex prevents religation of DNA strands, leading to double-strand DNA breaks, inhibition of nucleic acid synthesis, and ultimately, apoptotic cell death.
3. Indications & Uses
- AIDS-related Kaposi's Sarcoma (in patients with low CD4 counts and extensive mucocutaneous disease)
- Ovarian Cancer (platinum-refractory or recurrent)
- Multiple Myeloma (in combination with bortezomib for patients who have not previously received bortezomib and have received at least one prior therapy)
4. Dosage & Administration
Adult Dosage: Dosing is based on Body Surface Area (BSA). **AIDS-related Kaposi's Sarcoma:** 20 mg/m² IV over 30 minutes every 21 days. **Ovarian Cancer:** 50 mg/m² IV over 60 minutes every 28 days. **Multiple Myeloma:** 30 mg/m² IV over 60 minutes on day 4 following bortezomib (which is given on days 1, 4, 8, & 11) in a 21-day cycle.
Administration: For 20mg vial: Must be diluted in 250 mL of 5% Dextrose Injection (D5W). **DO NOT USE SALINE (0.9% Sodium Chloride) or any other diluent.** Administer via IV infusion using a dedicated line over 30-60 minutes as per indication. Use an inline, low-protein binding 0.22-micron filter. Strict aseptic technique. Observe for extravasation. Premedication with dexamethasone 10 mg IV (or equivalent) and an antihistamine (e.g., diphenhydramine 25-50 mg IV/PO) 30-60 minutes prior is standard in India to prevent infusion reactions.
5. Side Effects
Common side effects may include:
- Myelosuppression (Neutropenia, Anemia, Thrombocytopenia)
- Nausea and Vomiting (less severe than conventional doxorubicin)
- Stomatitis/Mucositis
- Alopecia (reduced severity compared to conventional)
- Fatigue/Asthenia
- Palmar-Plantar Erythrodysesthesia (PPE or Hand-Foot Syndrome) - dose-limiting
- Infusion-related reactions (flushing, shortness of breath, facial swelling)
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Trastuzumab, Cyclophosphamide (high-dose) | Markedly increased risk of cardiotoxicity (congestive heart failure, decreased LVEF). | Major |
| Other Myelosuppressive Agents (e.g., Paclitaxel, Gemcitabine) | Additive bone marrow suppression; increased risk of neutropenia, thrombocytopenia. | Major |
| Live Vaccines (e.g., MMR, Varicella, Yellow Fever) | Risk of disseminated infection due to immunosuppression. | Major |
| Phenytoin, Phenobarbital | Increased hepatic metabolism of doxorubicin, potentially reducing efficacy. | Moderate |
| Verapamil | May increase intracellular concentrations of doxorubicin, potentially increasing both efficacy and toxicity. | Moderate |
| Dexrazoxane | Cardioprotectant used to reduce the risk of anthracycline-induced cardiomyopathy. | Beneficial Interaction |
7. Patient Counselling
- DO report any signs of infection (fever, chills, sore throat) immediately.
- DO maintain good oral hygiene to reduce severity of mucositis.
- DO use effective contraception during and after treatment.
- DO inform all treating doctors and dentists about your chemotherapy.
- DONT receive any vaccinations without consulting your oncologist.
- DONT become pregnant or father a child during treatment.
- DONT consume grapefruit or its juice.
- DONT ignore symptoms of hand-foot syndrome (redness, pain, peeling on palms/soles).
8. Toxicology & Storage
Overdose: Exacerbation of acute toxicities: Severe myelosuppression (pancytopenia, sepsis), severe mucositis, gastrointestinal bleeding, and acute cardiotoxicity leading to fatal CHF.
Storage: Store unopened vials refrigerated at 2°C to 8°C. **DO NOT FREEZE.** Protect from light. The reconstituted/diluted solution in D5W is stable for up to 24 hours when refrigerated at 2°C to 8°C. Discard any unused portion. It is a cytotoxic drug; handle with appropriate precautions (gloves, gown, eye protection) during preparation and administration. Dispose as per hazardous waste protocols.