Guanidine (Oral)

Guanidine is used to treat muscle weakness and tiredness caused by Eaton-Lambert syndrome. Eaton-Lambert syndrome is an autoimmune disorder that affects the nervous system. Guanidine works on the nervous system to help restore muscle strength.

This medicine is available only with your doctor's prescription.

It is very important that your doctor checks your progress at regular visits to make sure this medicine is working properly. Blood and urine tests may be needed to check for unwanted effects.

This medicine lowers the number of some types of blood cells in your body. Because of this, you may bleed or get infections more easily. To help with these problems, avoid being near people who are sick or have infections. Wash your hands often. Stay away from rough sports or other situations where you could be bruised, cut, or injured. Brush and floss your teeth gently. Be careful when using sharp objects, including razors and fingernail clippers.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

In deciding to use a medicine, you need to think about the risks of taking it compared to the benefits it will provide. This decision is made together with your doctor. For this medicine, consider the following:

Allergies

Tell your doctor if you have ever had any unusual or allergic reactions to this medicine or any other medicines. Also inform your healthcare professional about any other allergies you may have, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Pediatric

There have not been appropriate studies on how age affects the effects of guanidine in children. Safety and effectiveness have not been established.

Geriatric

There is no information available on how age affects the effects of guanidine in older adults.

Breast Feeding

There are no adequate studies in women to determine the risk to infants when using this medication while breastfeeding. Weigh the potential benefits against the potential risks before taking this medication if you are breastfeeding.

Interactions with Medicines

Some medicines should not be used together at all, while in other cases, two different medicines may be used together even if an interaction might happen. In these situations, your doctor may adjust the dose, or other precautions may be necessary. It is especially important for your healthcare professional to know if you are taking any of the medicines listed below while using this medicine. The following interactions have been chosen based on their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is usually not recommended but may be necessary in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both.

• Amifampridine
• Bupropion
• Donepezil

Interactions with Food/Tobacco/Alcohol

Certain medicines should not be used around the time of eating or with specific types of food due to possible interactions. Using alcohol or tobacco with certain medicines may also cause interactions. Discuss with your healthcare professional about using your medicine with food, alcohol, or tobacco.

Other Medical Problems

Having other medical problems may affect the use of this medicine. Make sure to inform your doctor if you have any other medical issues, especially:

• Anemia (low red blood cells) or
• Kidney disease or
• Leukopenia (low white blood cells) or
• Mood changes, history of or
• Thrombocytopenia (low platelets in the blood)—Use with caution. May worsen these conditions.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do, they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

Incidence not known

• Ammonia-like breath odor
• black, tarry stools
• bleeding gums
• blood in the urine or stools
• blurred vision
• burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
• change in frequency or amount of urine
• chest pain
• chills
• cloudy urine
• cold sensations in the hands and feet
• confusion
• cough
• dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
• fast, irregular, pounding, or racing heartbeat or pulse
• fever
• increased thirst
• loss of appetite
• nausea or vomiting
• painful or difficult urination
• pale skin
• pinpoint red spots on the skin
• shakiness in the legs, arms, hands, or feet
• shortness of breath, especially with exercise
• sore throat
• sores, ulcers, or white spots on the lips or in the mouth
• sweating
• swollen glands
• unsteadiness, trembling, or problems with muscle control
• unusual bleeding or bruising
• unusual tiredness or weakness
• weight loss

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Incidence not known

• Abdominal or stomach cramps
• burning, itching, and pain in hairy areas
• crying for no reason
• dry mouth
• dryness and scaling of the skin
• false or unusual sense of well-being
• feeling irritated
• feeling of warmth
• feeling paranoid
• jitteriness
• large, flat, blue or purplish patches in the skin
• mood or mental changes
• pinpoint red or purple spots on the skin
• quick to react or overreact emotionally
• rash
• redness of the face, neck, arms, and occasionally, upper chest
• restlessness
• seeing or hearing things that are not there

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Pharmacologic Class: Cholinesterase Inhibitor

Take this medicine exactly as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered.

Dosing

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

• For oral dosage form (tablets):For Eaton-Lambert syndrome: Adults—Dose is based on body weight and must be determined by your doctor. The starting dose is usually between 10 and 15 milligrams (mg) per kilogram (kg) of body weight per day and divided in 3 or 4 doses. Your doctor may adjust your dose as needed. However, the dose is usually not more than 35 mg/kg/day. Children—Use and dose must be determined by your doctor.

Missed Dose

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.