Fondaparinux belongs to the class of medications called synthetic antithrombotics. It works by blocking clotting factors and enzymes that help the blood to clot. Circulating blood clots are dangerous because they can cause medical problems such as heart attack, stroke, and pulmonary embolism.

This medication is used to treat blood clots in deep veins (deep vein thrombosis [DVT]) and the lungs (pulmonary embolism [PE]). Fondaparinux can also be used to prevent blood clots for people who have unstable angina, have had a recent heart attack, or are undergoing certain types of surgery.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

The recommended dose of fondaparinux depends on the reason the medication is being used. The dose is injected subcutaneously or SC (under the skin), once daily. Sometimes, in a hospital setting, fondaparinux is given intravenously (into the vein).

To prevent clots after surgery, the dose is 2.5 mg injected once daily starting at least 6 hours after surgery.

When treating DVT or PE, the dose depends on body weight and ranges from 5 mg to 10 mg injected SC once daily.

For the management of heart attacks or severe angina, the dose is 2.5 mg SC once daily.

In all cases, it is important to continue using fondaparinux until your doctor has determined that the risk of blood clots has passed. This may be because you are mobile again after surgery or because another medication has been introduced to continue the clot prevention.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

If you are injecting this medication yourself, your doctor will show you how to use this medication properly. If you are not sure how to use it or have questions about how to use it, contact your doctor. Before using this medication, thoroughly read the patient information provided and ask your doctor if you have any questions. If a caregiver will be giving you the injections, your doctor should instruct them on how to give the injection.

To use this medication:

• Wash your hands and clean the injection site with an alcohol swab. Do not rub the injection site. Do not use it if the syringe is leaky, or if the medication appears cloudy or discoloured.
• Remove the needle shield. Avoid pressing on the syringe plunger so as not to lose any of the syringe content. Hold the syringe like a pencil.
• Pinch a fold of skin in the lower (left or right) region of your abdomen. Choose a different injection site for each injection so that you are not always injecting the same area.
• While holding the skin fold, insert the entire needle into the skin fold at a 90° angle to the skin and depress the syringe plunger completely.
• Remove the needle and let go of the syringe plunger. (The syringe will move into the device until the needle is guarded.)
• Apply pressure to the injection site with the alcohol swab for 5 to 10 seconds. Do not rub the injection site.
• Safely dispose of the used syringe device in approved containers, and keep it out of the reach of children.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature and keep out of reach of children.

2.5 mg/0.5 mL
Each 0.5 mL syringe prefilled with clear and colourless-to-slightly-yellow liquid contains 2.5 mg of fondaparinux sodium. Nonmedicinal ingredients: sodium chloride, water for injection, and sodium hydroxide or hydrochloric acid for pH adjustment.

7.5 mg/0.6 mL
Each 0.6 mL syringe prefilled with clear and colourless-to-slightly-yellow liquid contains 7.5 mg of fondaparinux sodium. Nonmedicinal ingredients: sodium chloride, water for injection, and sodium hydroxide or hydrochloric acid for pH adjustment.

Do not take this medication if you:

• are allergic to fondaparinux or any ingredients of the medication
• have excessive bleeding
• have a bacterial infection of the heart or heart valves
• have a low level of platelets in the blood and anti-platelet antibodies

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• constipation
• coughing
• diarrhea
• dizziness
• drowsiness
• flushing
• headache
• heartburn
• rash
• reactions at the injection site (e.g., pain, bruising, redness)
• spinning sensation
• stomach pain
• swelling in the feet, ankles, or wrists
• tiredness
• trouble sleeping

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• anxiety
• bruises that are joining together
• chest pain
• confusion
• infection at the surgery site (e.g., heat, redness, swelling, oozing of fluid)
• leg pain
• loss of consciousness
• low blood pressure (e.g., lightheadedness, dizziness, or fainting)
• shortness of breath
• signs of anemia (low red blood cells; e.g., dizziness, pale skin, unusual tiredness or weakness, shortness of breath)
• signs of clotting problems (e.g., unusual nosebleeds, bruising, blood in urine, coughing blood, bleeding gums, cuts that don’t stop bleeding)
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• signs of low potassium levels in the blood (e.g., weakness, fatigue, muscle cramps, irregular heartbeat)
• symptoms of a urinary tract infection (e.g., pain when urinating, urinating more often than usual, low back or flank pain)
• wounds oozing

Stop taking the medication and seek immediate medical attention if any of the following occur:

• signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)
• signs of bleeding in the stomach (e.g., bloody, black, or tarry stools; spitting up of blood; vomiting blood or material that looks like coffee grounds)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Bleeding: This medication can increase the risk of unwanted or uncontrolled bleeding, particularly if you have a bleeding disorder, ulcers of the digestive system or a recent episode of bleeding after brain, spine, or eye surgery. People who weigh less than 50 kg may also have an increased risk of bleeding. If you believe you may have an increased risk of bleeding problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Kidney function: Kidney disease or reduced kidney function may cause this medication to build up in the body, causing side effects. If you have reduced kidney function or kidney disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Latex allergy: The needle shield of the pre-filled syringe contains dry natural latex rubber. If you are allergic to latex, this may cause an allergic reaction.

Spinal/epidural hematomas: There have been cases of spinal bleeding and blood clots when antithrombotic medications are used along with spinal or epidural anesthesia. These spinal blood clots may lead to long-term or permanent paralysis. The risk may be greater if people are taking other medications that affect blood clotting (e.g., nonsteroidal anti-inflammatory drugs [NSAIDs] such as naproxen or ibuprofen, or other anticoagulants), or in people who require repeated epidural or spinal procedures. If you notice a sudden inability to move your body or sudden back pain or tenderness, get medical help immediately.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if fondaparinux passes into breast milk. If you are breast-feeding and taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children less than 17 years old.

Seniors: People over the age of 65 years old may be more at risk of bleeding from this medication.

For a full list of interactions, use the Drug Interaction Checker available on the Drugs.com website.

If you are taking other medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.