CYCLOPHOSPHAMIDE (Cytoxan) |
Description
Cyclophosphamide (Cytoxan) belongs to a class of drugs known
as alkylating agents, which were originally developed and are still used
to treat some types of cancer. It is in the class of medications referred
to as immunosuppressants – medicines that can decrease the immune response.
Uses
Cyclophosphamide is used in the treatment of
lupus,
systemic
sclerosis (scleroderma), some forms of vasculitis
,myopathies such as polymyositis and dermatomyositis, as well as some complications of
rheumatoid
arthritis.
In rheumatoid arthritis, it is usually reserved for individuals with complicated disease, such as those with vasculitis or blood vessel inflammation in addition to their arthritis. In lupus, it is generally used for patients who develop serious kidney problems. Although cyclophosphamide has improved survival time in people with some of the diseases listed, this medication requires monitoring as it can cause serious side effects. Cyclophosphamide is not used to treat arthritis itself except in very unusual circumstances.
How it works
Cyclophosphamide interferes with the deoxyribonucleic acid (DNA) in cells. This prevents cells from dividing, leading to cell death. Some of the cells affected by this medication are immune cells, which are involved in the development of autoimmune diseases such as rheumatoid arthritis, lupus, scleroderma or vasculitis.
Dosing
The dosing of cyclophosphamide varies from person to person and depends on the disease being treated. For the form taken by mouth, a usual dose is 1.5 to 2.5 milligrams (mg) per kilogram of body weight per day. This medication also is given in an intravenous (IV) form in the doctor's office or hospital.
Time to effect
It may take several weeks for symptoms to improve, and the full effect may take several months or longer.
Side Effects
Common side effects, which may be worse with the oral preparation, include nausea and vomiting. These symptoms can usually be controlled with anti-nausea medications. Hair loss can occur, but hair will grow back when the medication is stopped. Other common side effects include skin rashes. Cyclophosphamide increases the risk of developing some kinds of infections, especially herpes zoster, often referred to as “shingles.”
Other important side effects include:
Blood cells: Cyclophosphamide can have significant effects on the blood cells, typically causing a reduction in the number of white blood cells, a key component of the body's immune system. This often occurs approximately 8-12 days after starting treatment. Your doctor will check your blood counts around this time and make dose adjustments as needed.
Fertility problems: Cyclophosphamide can cause infertility in both men and women, most often in older patients or those taking higher doses for long periods of time. Discuss this issue with your doctor before taking cyclophosphamide. Although women taking cyclophosphamide can stop having periods, they can still become pregnant so an effective form of birth control to prevent pregnancy should be used while taking this medication. Taking cyclophosphamide during pregnancy is very dangerous to an unborn child.
Bladder problems: Cyclophosphamide is broken down in the body into several other products. One byproduct known as acrolein can cause an irritation of the bladder, or “cystitis,” which may result in blood in the urine or scarring of the bladder. To avoid this common side effect, patients taking oral cyclophosphamide should drink plenty of fluids each day. Patients receiving intravenous therapy are sometimes given a medication called mesna ( Mesnex) to help prevent bladder problems.
Cancers: Cyclophosphamide increases the risk of a form of bladder cancer as well as other cancers, which can occur years after taking this medication. Individuals taking higher or longer-term doses of cyclophosphamide are at greater risk for developing cancers. Bladder cancer is the most common cancer related to cyclophosphamide, so your doctor will recommend periodic urine tests to screen for this.
Points to remember
Because cyclophosphamide can cause serious birth defects, women who are pregnant or considering having a child should talk with their doctor before taking this drug. To avoid pregnancy, use an effective form of birth control throughout the course of this treatment. Also talk with your doctor about breast-feeding while on this medication.
Some of the side effects of cyclophosphamide may be serious, so contact your doctor if you notice: blood in your urine, fevers and chills, easy bruising or bleeding, shortness of breath or swelling of the feet and ankles.
Because cyclophosphamide use increases the risk of infection, some doctors suggest that patients take a concurrent antibiotic called trimethoprim sulfa (Bactrim), unless there is an allergy to sulfa medications. Be sure to talk with your doctor before receiving any vaccines and undergoing any surgeries while taking this medication.
Drug Interactions
Let your physician know all medications you are taking, including over-the-counter medicines and herbal supplements. Important drug interactions can occur with cyclophosphamide and the following medications: the gout medication allopurinol (Aloprim, Zyloprim), phenobarbital (Solfoton), warfarin (Coumadin), thiazide diuretics, such as hydrochlorothiazide, and some psychiatric medications. Other medications also can interfere with cyclophosphamide.
For more information
The American College of Rheumatology has compiled this list to give you
a starting point for your own additional research. The ACR does not endorse
or maintain these Web sites, and is not responsible for any information
or claims provided on them. It is always best to talk with your rheumatologist
for more information and before making any decisions about your care.
National Institutes of Health: Medline Plus Link
http://www.nlm.nih.gov/medlineplus/druginfo/medmaster/a682080.html
Updated June 2006
Written by Michael Cannon, MD, and reviewed by the American College of
Rhematology Patient Education Task Force.
