S)-ethambutol
S)-ethambutol Uses, Dosage, Side Effects, Food Interaction and all others data.
S)-ethambutol appears to inhibit the synthesis of 1 or more metabolites in susceptible bacteria resulting in impairment of cellular metabolism, arrest of multiplication, and cell death. It is active against susceptible bacteria only when they are undergoing cell division.
S)-ethambutol is indicated in combination with other anti-tuberculosis drugs in the treatment of pulmonary tuberculosis. It has a long duration of action as it is administered daily, and a moderate therapeutic window. Patients should be counselled regarding the risk of optic neuritis and hepatic toxicity.
| Trade Name | S)-ethambutol |
| Availability | Prescription only |
| Generic | Ethambutol |
| Ethambutol Other Names | (S,S)-ethambutol, Etambutol, Etambutolo, Ethambutol, Ethambutolum, S,S-Ethambutol |
| Related Drugs | ciprofloxacin, azithromycin, levofloxacin, Zithromax, Levaquin, clarithromycin, rifampin, Biaxin, rifabutin |
| Type | |
| Formula | C10H24N2O2 |
| Weight | Average: 204.3098 Monoisotopic: 204.183778022 |
| Protein binding | Ethambutol is 20-30% bound to protein in plasma. Data regarding which proteins ethambutol binds to are not readily available. |
| Groups | Approved |
| Therapeutic Class | Anti-Tubercular Chemotherapeutics. |
| Manufacturer | |
| Available Country | |
| Last Updated: | September 19, 2023 at 7:00 am |
Uses
S)-ethambutol is used for the treatment of pulmonary tuberculosis. It should not be used as the sole antituberculous drug, but should be used in conjunction with at least one other antituberculous drug. Selection of the companion drug should be based on clinical experience, considerations of comparative safety, and appropriate in vitro susceptibility studies. In patients who have not received previous antituberculous therapy, ie, initial treatment, the most frequently used regimens have been the following:
- S)-ethambutol plus isoniazid
- S)-ethambutol plus isoniazid plus streptomycin.
In patients who have received previous antituberculous therapy, mycobacterial resistance to other drugs used in initial therapy is frequent. Consequently, in such retreatment patients, S)-ethambutol should be combined with at least one of the second line drugs not previously administered to the patient and to which bacterial susceptibility has been used by appropriate in vitro studies. Antituberculous drugs used with S)-ethambutol have included cycloserine, ethionamide, pyrazinamide, viomycin and other drugs. Isoniazid, aminosalicylic acid, and streptomycin have also been used in multiple drug regimens. Alternating drug regimens have also been utilized.
S)-ethambutol is also used to associated treatment for these conditions: Mycobacterium Infections, Mycobacterium avium complex infection, Pulmonary Tuberculosis (TB)
How S)-ethambutol works
S)-ethambutol diffuses into Mycobacterium cells. Once inside the cell, ethambutol inhibits the arabinosyltransferases (embA, embB, and embC), preventing formation of the cell wall components arabinogalactan and lipoarabinomannan, and preventing cell division. Decreased concentrations of arabinogalactan in the cell wall reduces the number of binding sites for mycolic acid, leading to the accumulation of mycolic acid, trehalose monomycolate, and trehalose dimycolate. Lipoarabinomannan is a component of a cell surface molecule involved in the interaction with host cells. Reduced levels of lipoarabinomannan may interfere with mycobacterial interaction with host cells.
Dosage
S)-ethambutol dosage
S)-ethambutol should not be used alone, in initial treatment or in retreatment. S)-ethambutol should be administered on a once every 24-hour basis only.Absorptionis not significantly altered by administration with food. Therapy, in general, should be continued until bacteriological conversion has become permanent and maximal clinical improvement has occurred.
S)-ethambutol is not recommended for use in pediatric patients under thirteen years of age since safe conditions for use have not been established.
Initial Treatment:In patients who have not received previous antituberculous therapy, administer S)-ethambutol 15 mg/kg of body weight, as a single oral dose once every 24 hours. In the more recent studies, isoniazid has been administered concurrently in a single, daily, oral dose.
Retreatment:In patients who have received previous antituberculous therapy, administer S)-ethambutol 25 mg/kg of body weight, as a single oral dose once every 24 hours. Concurrently administer at least one other antituberculous drug to which the organisms have been demonstrated to be susceptible by appropriatein vitrotests. Suitable drugs usually consist of those not previously used in the treatment of the patient. After 60 days of S)-ethambutol administration, decrease the dose to 15 mg/kg of body weight, and administer as a single oral dose once every 24 hours.
During the period when a patient is on a daily dose of 25 mg/kg, monthly eye examinations are advised.
Renal Impairment: Dose adjustment may be needed as determined by blood levels of ethambutol.
Should be taken with food.
Side Effects
Retrobulbar neuritis with reduction in visual acuity, constriction of visual field, central or peripheral scotoma and green-red colour blindness of 1 or both eyes. Reduced renal clearance of urate and may precipitate acute gout. Confusion, disorientation, hallucinations, headache, dizziness, malaise, jaundice or transient liver dysfunction, peripheral neuropathy, thrombocytopenia, pulmonary infiltrates, eosinophilia and GI disturbances (e.g. nausea, vomiting, anorexia, abdominal pain). Rarely, retinal haemorrhage, hypersensitivity reactions including rashes, pruritus, leucopenia, fever, and joint pains.
Toxicity
Patients experiencing a chronic overdose of ethambutol may present with disturbances in colour vision and reduced visual acuity as symptoms of optic neuropathy. In these cases, ethambutol should be stopped. Data regarding acute overdose of ethambutol are not readily available. Patients experiencing an acute overdose of ethambutol may be experience an increased risk and severity of adverse effects such as pruritus, joint pain, gastrointestinal upset, abdominal pain, malaise, headache, dizziness, mental confusion, disorientation, and possible hallucinations. Patients should be treated with symptomatic and supportive measures.
Precaution
Patient with ocular defects (e.g. cataracts, recurrent ocular inflammatory conditions, diabetic neuropathy). Renal impairment. Pregnancy and lactation.
Interaction
Delayed or reduced absorption with aluminium hydroxide.
Food Interaction
- Take separate from antacids. Do not take aluminum hydroxide containing antacids for at least 4 hours after ethambutol administration.
- Take with food. Food reduces irritation.
S)-ethambutol Drug Interaction
Unknown: fluticasone / salmeterol, fluticasone / salmeterol, acetaminophen, acetaminophen, montelukast, montelukast, tiotropium, tiotropium, acetaminophen, acetaminophen, multivitamin, multivitamin, cyanocobalamin, cyanocobalamin, pyridoxine, pyridoxine, ascorbic acid, ascorbic acid, cholecalciferol, cholecalciferol
S)-ethambutol Disease Interaction
Major: optic neuritisModerate: hepatic impairment, hyperuricemia, renal dysfunction
Volume of Distribution
Patients coinfected with tuberculosis and HIV have an estimated ethambutol volume of distribution of 76.2 L.
Elimination Route
Oral ethambutol is approximately 75-80% orally bioavailable. A 25 mg/kg oral dose of ethambutol reaches a Cmax of 2-5 µg/mL, with a Tmax of 2-4 hours. In a separate study, the AUC0-8 varied from 6.3 ± 5.5 h*mg/L to 10.8 ± 7.6 h*mg/L depending on CYP1A2 genetic polymorphisms.
Half Life
S)-ethambutol has a half life of 3.3 hours in patients with normal renal function. In patients with renal failure, the half life could be 7 hours or longer.
Clearance
Patients coinfected with tuberculosis and HIV have an estimated ethambutol oral clearance of 77.4 L/h.
Elimination Route
S)-ethambutol is 50% eliminated in the urine as the unmetabolized parent compound and 8-15% as inactive metabolites. 20-22% of a dose is eliminated unchanged in the feces.
Pregnancy & Breastfeeding use
Category C: Either studies in animals have revealed adverse effects on the foetus (teratogenic or embryocidal or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the foetus.
Contraindication
S)-ethambutol is contraindicated in patients who are known to be hypersensitive to this drug. It is also contraindicated in patients with known optic neuritis unless clinical judgment determines that it may be used. S)-ethambutol is contraindicated in patients who are unable to appreciate and report visual side effects or changes in vision.
Storage Condition
Store between 20-25°C. Protect from light, moisture and excessive heat.
Innovators Monograph
You find simplified version here S)-ethambutol
S)-ethambutol contains Ethambutol see full prescribing information from innovator S)-ethambutol Monograph, S)-ethambutol MSDS, S)-ethambutol FDA label
FAQ
What is S)-ethambutol used for?
S)-ethambutol is used to treat tuberculosis (TB). It is used with other medicines for TB. This medicine may also be used for other problems as determined by your doctor. It is usually given in combination with other tuberculosis medications, such as isoniazid, rifampicin and pyrazinamide. It may also be used to treat Mycobacterium avium complex, and Mycobacterium kansasii.
How safe is S)-ethambutol?
A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.
How does S)-ethambutol work?
S)-ethambutol is an antibiotic and works by stopping the growth of bacteria.
What are the common side effects of S)-ethambutol?
Headache, loss of appetite, upset stomach, or nausea/vomiting may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly. Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects.
Is S)-ethambutol safe during pregnancy?
S)-ethambutol is recommended for use in pregnancy without any specific precautions. Its use in high therapeutic doses in neonates/infants is generally discouraged, because of eye toxicity concerns and the availability of better treatment options, but its use in pregnancy is not discouraged.
Is S)-ethambutol safe during breastfeeding?
S)-ethambutol are the only agents considered by the AAP to be compatible with breastfeeding.
Can I drink alcohol with S)-ethambutol?
Do not drink alcohol while taking this medicine. You could damage your liver. If this is not possible, limit your intake to one to two drinks per week.
Can I drive after taking S)-ethambutol?
After taking your medicine you should not drive or use machinery until you know how S)-ethambutol affects you. Always take S)-ethambutol Tablets exactly as your doctor has told you to.
How do I take S)-ethambutol?
Take this S)-ethambutol by mouth with or without food, usually once daily or as directed by your doctor.
How often can I take S)-ethambutol?
S)-ethambutol usually once daily or as directed by your doctor. This medication may sometimes be taken twice weekly. Take this S)-ethambutol exactly as directed by your doctor.
How much S)-ethambutol can I take daily?
Adults and children 13 years of age and older 15 to 25 milligrams (mg) per kilogram (kg) (6.8 to 11.4 mg per pound) of body weight once a day. Instead, your doctor may tell you to take 50 mg per kg (22.8 mg per pound) of body weight, up to a total of 2.5 grams, two times a week.
How long does S)-ethambutol stay in my system?
When the S)-ethambutol is administered daily for longer periods of time at this dose, serum levels are similar. The serum level of S)-ethambutol falls to undetectable levels by 24 hours after the last dose except in some patients with abnormal renal function.
How long can I take S)-ethambutol?
You may have to take it every day for as long as 1 to 2 years or more. It is important that you do not miss any doses.
When should I stop taking S)-ethambutol?
S)-ethambutol can cause vision problems that may be a sign that you should stop taking the medicine. You may not be able to take S)-ethambutol if you cannot recognize or report any changes in your vision.
Who should not take S)-ethambutol?
You should not use S)-ethambutol if you are allergic to it. You may not be able to take ethambutol if you have an eye condition called optic neuritis (inflammation of nerve fibers behind your eyes). Your doctor will decide if this treatment is right for if you have an eye disorder.Tell your doctor if you are pregnant or plan to become pregnant while using this medicine. S)-ethambutol can pass into breast milk and may harm a nursing baby. Tell your doctor if you are breast-feeding a baby. S)-ethambutol should not be given to a child younger than 13 years old.
What happens if I miss a dose?
Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.
Can I overdose on S)-ethambutol?
If you take too much S)-ethambutol, call your local Poison Control Center or seek emergency medical attention right away.
Can S)-ethambutol cause kidney damage?
Acute kidney injury (AKI) is a rare and severe complication that can interrupt treatment and cause permanent kidney damage.
Can S)-ethambutol affects my liver?
S)-ethambutol therapy has been associated with minor, transient and asymptomatic elevations in serum aminotransferase levels, and is a reported but rare cause of clinically apparent acute liver injury.
Does S)-ethambutol cause hearing loss?
S)-ethambutol– 1200 mg OD (antibacterial agent). The individual was on these drugs for last 10 month. The patient reported hearing difficulty and other symptoms were initiated after 9 months of MDR-TB medication.
