What is lomustine?
Lomustine (brand names: Gleostine®, CeeNU®) is an antineoplastic (anticancer) chemotherapy used to treat brain and spinal cord tumors, mast cell tumors, histiocytic sarcomas, or lymphoma.
Its use in cats and dogs to treat certain cancers is off label (extra label). Many drugs are commonly prescribed for off-label use in veterinary medicine. “Off label” means the drug is being used in a way that has not been reviewed or approved by the U.S. Food and Drug Administration (FDA) or Health Canada. In these instances, follow your veterinarian’s directions and cautions carefully, as they may be significantly different from those on the label.
How is lomustine given?
- Lomustine is given by mouth in the form of a capsule. It may also be compounded into other forms such as chewable tablets and liquid suspensions.
- Measure liquid forms very carefully.
- Give lomustine with food.
- On the day your pet receives this medication, and for a few days afterward, use gloves when handling all bodily waste such as urine, feces, cat litter, blood, or vomit. Throw this waste in a sealable plastic bag, then seal this bag and the gloves in another sealable bag and dispose in the regular garbage.
Lomustine is considered a hazardous drug, so it is essential to avoid accidental exposure. Wear gloves when handling the medication and do not handle it if you are pregnant or nursing. If your pet vomits after receiving this drug, wear gloves while cleaning up.
This medication can take a few weeks before full effects are noted, but side effects can occur immediately. Gradual improvements are usually noticeable after a few days.
What if I miss giving my pet the medication?
If you miss a dose, contact your veterinarian for further instructions, as this medication must be dosed very carefully.
Are there any potential side effects?
Lomustine may cause the following side effects:
- Lack of appetite, vomiting, diarrhea
- Sores in the mouth
- Hair loss
- Eye ulcers
Serious adverse reactions may occur. If any of the following signs develop, stop giving lomustine and contact your veterinarian immediately:
- Bruising
- Bleeding
- Fever
- Severe lethargy
- Changes in urination
- Yellowing of the skin or eyes
- Shortness of breath
Drug sensitivities can develop over time, with repeated exposure. Your pet may have no reaction after the first few doses but may develop a sensitivity later. It is important to watch for signs of an allergic reaction over the entire course of treatment.
Other side effects may occur. If you notice anything unusual, contact your veterinarian immediately. This moderate-acting medication should stop working in a few days, although effects can be longer in pets with liver or kidney disease.
Are there any risk factors for this medication?
DO NOT USE lomustine in:
- Pets that are severely allergic to it
USE WITH EXTREME CAUTION in:
- Pets with anemia, bone marrow problems, or active infections (use only when the potential benefits outweigh the risks)
- Pets with liver, kidney, or lung dysfunction (use only when the potential benefits outweigh the risks)
- Pets that are pregnant (use only when the potential benefits to the mother outweigh the risks to the offspring)
- Pets that are lactating (if use is necessary, use a milk replacer)
Do not handle this medication if you are pregnant.
Are there any drug interactions I should be aware of?
Several medications should be used with caution when given with lomustine, including:
- Myelosuppressive agents
- Vaccines
Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking before starting any new treatment.
Is any monitoring needed with this medication?
- Liver, kidney, and lung function tests should be performed before starting the treatment and immediately prior to the next scheduled dose.
- Complete blood counts should be performed one week after dosing and immediately prior to the next scheduled dose to evaluate your pet’s fitness to receive that dose.
- Your veterinarian will let you know when and how they want to reassess your pet to ensure the medication is working and not causing side effects.
- At home, monitor for any side effects such as those noted above. If any occur, stop using the medication and contact your veterinarian.
How do I store lomustine?
- Store this medication in a sealed container at room temperature between 68°F and 77°F (20°C and 25°C).
- Do not expose this medication to temperatures above 104°F (40°C).
- Protect from light.
What should I do in case of emergency?
If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility. Be prepared to provide information about the product and your pet's weight and symptoms.
