How does this medication work? What will it do for me?

Chlorpropamide belongs to a group of medications called sulfonylureas. It is used to lower blood sugar for people with type 2 diabetes when diet, exercise, and weight loss have not controlled blood sugar well enough.

It works by stimulating the release of insulin, which lowers blood sugar and helps to make the body more sensitive to the effects of insulin. This medication usually starts to work within 1 week, but it may take up to 4 weeks to see its full effect.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. As well, some forms of this medication may not be used for all of the conditions discussed here. 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.

What form(s) does this medication come in?

100 mg
Each white, round, flat-faced, scored tablet, engraved "APO" over "100" contains chlorpropamide 100 mg. Nonmedicinal ingredients: calcium hydroxide, colloidal silicon dioxide, croscarmellose sodium, magnesium stearate, and microcrystalline cellulose.

250 mg
Each white, oval, biconvex, scored film-coated tablet, engraved "APO 250" on one side, contains chlorpropamide 250 mg. Nonmedicinal ingredients: calcium hydroxide, carnauba wax, colloidal silicon dioxide, croscarmellose sodium, hydroxypropyl methylcellulose, magnesium stearate, microcrystalline cellulose, polyethylene glycol (carbowax), and titanium dioxide.

How should I use this medication?

The recommended dose of chlorpropamide ranges from 100 mg to 500 mg once daily taken with breakfast.

The usual initial dose is 250 mg daily. For seniors, the initial dose is usually lower and ranges from 100 mg to 125 mg daily. If stomach upset occurs, larger doses can be split into two and taken with breakfast and supper when suggested by your doctor.

Many things can affect the dose of a 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.

It is important that this medication be taken 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, protect it from light and moisture, and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Chlorpropamide should not be taken by anyone who:

  • is allergic to chlorpropamide or to any of the ingredients of this medication
  • is pregnant
  • is undergoing surgery
  • has a serious infection
  • has ketoacidosis (buildup of ketones in the blood)
  • has serious kidney, liver, or thyroid dysfunction
  • has suffered from recent severe trauma
  • has type 1 (or insulin-dependent) diabetes
  • has very poor blood glucose control

What side effects are possible with this medication?

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.

  • a feeling of fullness
  • heartburn
  • nausea
  • weight gain

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

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

  • severe skin rash or blistering, peeling skin
  • skin rash or itchy skin
  • symptoms of low blood sugar
    • dizziness
    • drowsiness
    • headache
    • lack of energy
    • nervousness
    • numbness or tingling
    • shakiness
    • sweating
    • weakness
  • yellowing of the skin or whites of eyes (jaundice)

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

  • signs of a severe allergic reaction (such as difficulty breathing, hives, swelling of the face or throat)

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.

Are there any other precautions or warnings for 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.

Allergy: People who are allergic to sulfa medications may also be allergic to chlorpropamide.

Blood sugar control: For people with diabetes, loss of blood sugar control may occur during illness or stressful situations such as trauma or surgery. Under these conditions, your doctor may recommend or prescribe insulin until the situation improves.

Diabetes complications: Chlorpropamide has not been proven to prevent the development of complications associated with diabetes.

Hemolytic anemia: People with a genetic deficiency of glucose-6-phosphate dehydrogenase (G6PD) should not take this medication as it may cause hemolytic anemia (a rapid destruction of red blood cells).

Low blood sugar: This medication can cause low blood sugar (hypoglycemia). This is more likely to occur for people with reduced kidney or liver function or who are malnourished, not eating enough, exercising vigorously, or have reduced adrenal gland function. Symptoms of low blood sugar include:

  • dizziness
  • drowsiness
  • headache
  • lack of energy
  • nervousness
  • numbness or tingling
  • shakiness
  • sweating
  • weakness

People taking this medication should monitor their blood sugar regularly and keep emergency glucose available to treat low blood sugar levels. Contact your doctor if you experience low blood sugar while taking this medication.

Reduced response: Over a period of time, people may become less responsive to medications such as chlorpropamide because of worsening of their diabetes. If your blood sugar levels are not controlled while taking this medication, contact your doctor.

Pregnancy: Chlorpropamide should not be used during pregnancy. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: Chlorpropamide passes into breast milk and is not recommended for women who are breast-feeding.

Children: The safety and effectiveness of using this medication for children have not been established.

What other drugs could interact with this medication?

There may be an interaction between chlorpropamide and any of the following:

  • ACE inhibitors (e.g., ramipril, enalapril, perindopril)
  • acetazolamide
  • alcohol
  • anabolic steroids or male sex hormone (e.g., testosterone)
  • barbiturates (e.g., phenobarbital, butalbital)
  • beta-blockers (e.g. propranolol, acebutolol)
  • chloramphenicol
  • clarithromycin
  • clofibrate
  • corticosteroids (e.g., prednisone, dexamethasone)
  • cyclophosphamide
  • diazoxide
  • disopyramide
  • epinephrine
  • fenfluramine
  • fenofibrate
  • fluconazole
  • fluorouracil
  • fluoxetine
  • gemfibrozil
  • hydrochlorothiazide
  • isoniazid
  • ketoconazole
  • levothyroxine
  • liraglutide
  • MAO inhibitors (e.g., phenelzine, tranylcypromine)
  • nicardipine
  • nicotinic acid
  • NSAIDs (e.g., ibuprofen, ketorolac)
  • oral contraceptives or estrogen
  • other medications used to lower blood sugar (e.g., insulin, glyburide, gliclazide)
  • phenothiazines (e.g., haloperidol)
  • phenylbutazone
  • phenylephrine
  • phenytoin
  • probenecid
  • pseudoephedrine
  • quinolone antibiotics (e.g., ciprofloxacin, moxifloxacin)
  • rifampin
  • salicylates (e.g., acetylsalicylic acid - ASA)
  • sulfinpyrazone
  • sulfonamides
  • tetracycline
  • thyroid medication
  • warfarin

If you are taking any of these 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.

Medications other than those listed above may interact with this medication. 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.