MECHANISM OF ACTIONDapsone is an antibiotic used in cases of leprosy, along with other antibiotics (rifampicin and clofazimine). Dapsone also has an anti-inflammatory effect in several non-bacterial diseases, such as the skin disease dermatitis herpetiformis (Dühring's disease). Dapsone is registered for these two diseases (leprosy and the blistering disease dermatitis herpetiformis), but is also prescribed for other conditions.DOSAGEFor leprosy, the dosage for adults is 100 mg per day. This is part of the triple therapy for leprosy: 100 mg dapsone per day + 50 mg clofazimine per day and 600 mg rifampicin + 300 mg clofazimine once a month.
For dermatitis herpetiformis, the dosage varies considerably. Usually, the initial dose is 50-100 mg per day, after which the dosage is adjusted based on the effect.
For children, the dosage should be adjusted based on body weight.DOSAGE FORMSDapsone (diaphenylsulfone) is available as a 100 mg tablet (divisible).
It is available by prescription only and is fully covered by insurance.HOW SHOULD DAPSON BE TAKEN?Take the tablets with water. Place them on the back of the tongue and swallow with half a glass of water. Sometimes a very low dose is needed, e.g., 25 mg per day. In that case, the tablet can be broken into quarters. Alternatively, take half a tablet (50 mg) per day. For higher doses, e.g., 200 mg per day, divide the daily dose into two doses (e.g., 100 mg in the morning and 100 mg in the evening).
WHEN NOT TO USE? (contraindications)
- in case of hypersensitivity to dapsone
- in case of severe anaemia
- in case of a severe deficiency of the enzyme G6PD (a congenital defect)
- in case of acute porphyria (a metabolic disorder in which the production and breakdown of red blood pigment is abnormal)
TAKE EXTRA CAUTION WITH DAPSON:- in case of a mild to moderate deficiency of the enzyme G6PD (a congenital defect)
- in case of heart and lung diseases
- in case of kidney or liver function disordersWHAT ARE THE POSSIBLE SIDE EFFECTS?- nausea, vomiting, stomach and abdominal complaints, loss of appetite
- allergic reactions, itching, fever (allergic reactions usually begin after 3-6 weeks)
- skin reactions (various reactions including Stevens-Johnson syndrome, toxic epidermal necrolysis, dapsone hypersensitivity
syndrome, DRESS)
- sensitivity to sunlight
- headache
- insomnia, confusion, dizziness
- blurred vision, tinnitus
- increased heart rate
- infertility in men
- anemia, blood breakdown, jaundice
- low number of white blood cells
- damage to the kidneys or liver
- damage to nerves (impaired sense of touch) or muscles (muscle weakness)
- nervousness, depressed mood, thought disorders, delusions
Anemia and blood breakdown occur mainly in people who lack a certain enzyme (G6PD enzyme). This occurs in families and in certain breeds. Before starting treatment, a blood test can be done to determine whether there is a G6PD deficiency. If there is a deficiency of this enzyme, dapsone should be used with caution and Hb (hemoglobin) levels should be closely monitored. The first symptoms of anemia are fatigue and pallor, or jaundice (due to hemoglobin breakdown).OVERDOSAGEIf you take too much dapsone, contact your doctor immediately. Symptoms may include blue discoloration of the skin and mucous membranes, shortness of breath, nausea and vomiting, jaundice, nervous system disorders, severe anemia and other blood abnormalities, impaired kidney function, and loss of consciousness (coma). Keep tablets out of reach of children (this always applies to medications).WHAT SHOULD I DO IF I MISS A DOSE?If you take 100 mg daily and you forgot to take a tablet yesterday: take 100 mg today, or earlier if necessary, but do not take a double dose (do not 'catch up' on tablets).INTERACTIONS WITH OTHER MEDICINESAn interaction means that medications can influence each other's effects or side effects when used simultaneously. This does not mean that simultaneous use is always prohibited; these interactions simply need to be taken into account when prescribing. The following medications may interact with dapsone:
- rifampicin
- pyrimethamine
- para-aminobenzoic acid
- activated charcoal
- folic acid antagonists
- probenecid.
If you are unsure whether any of the above interactions apply to you, contact your pharmacist or doctor. Also, make sure your doctor is fully aware of any other medications you are taking. Report any changes, and always bring a list of your medications with you when you visit the doctor. The pharmacist also monitors interactions. If you have a regular pharmacy, all medications you use are registered in the computer system, and that system automatically alerts you if medications are prescribed that are incompatible. In such a case, the pharmacist will contact the prescribing physician and, in consultation, a decision can then be made to adjust the medication or accept the risk of the interaction.DRIVING, WORK AND SPORTSThis medication can—in rare cases—cause visual disturbances (blurred vision) as a possible side effect, thus negatively impacting reaction time and concentration.
This can seriously impair all kinds of daily activities, such as household chores, driving, and operating machinery.PREGNANCY AND BREASTFEEDINGPregnancy: Insufficient data are available on this medication to properly assess its potential harm during pregnancy. Therefore, only use this medication during pregnancy after consulting your doctor (in exceptional circumstances, when there are no suitable alternatives, it may still be prescribed during pregnancy).
Breastfeeding: The active ingredient is excreted in breast milk. This may cause a certain form of anemia (hemolytic anemia) in the infant. Therefore, you should not breastfeed while taking this medication.HOW TO STORE?Store dapsone tablets in their packaging at room temperature. Young children often mistake medicines for food, drink, or candy. Therefore, always keep medicines out of reach of young children! Most medicines have a good shelf life in their original packaging at room temperature. Do not store medicines in a warm and/or humid environment, such as a shower cubicle or bathroom.
The expiration date of a medicine is stated on the packaging.
Do not store, give to others, or dispose of excess medicine in the trash or toilet. It is best to return it to the pharmacy.STOPPING DAPSONSide effects may be a reason to stop. However, don't just stop immediately; contact your doctor. It may be possible to keep the side effects within reasonable limits by lowering the dose. Also consult your doctor if any of the above side effects bother you too much, or if you experience other side effects that concern you.
If stopping is absolutely necessary, dapsone can be stopped immediately. |
