Rifabutin

Rifabutin is an antibiotic from the rifampicin group. It is used to treat a variety of bacterial infections, including tuberculosis and infections caused by Mycobacterium avium complex (MAC) that can occur in patients with HIV infection.

Rifabutin works by inhibiting the growth and reproduction of bacteria, including Mycobacterium tuberculosis, the bacterium that causes tuberculosis, and MAC. This medicine is usually taken orally in capsule or tablet form.

In addition to treating tuberculosis and infections caused by MAC, rifabutin may also sometimes be used to prevent or treat other bacterial infections as recommended by your doctor.

It is important to take rifabutin only as prescribed by your doctor and to follow the recommendations for dosage and duration of treatment. As with any antibiotic, side effects may occur and it is important to monitor and discuss them with your doctor.

Indications Rifabutin

1. Tuberculosis: Rifabutin is often used in combination with other antibiotics to treat tuberculosis caused by Mycobacterium tuberculosis. It can be used in both primary treatment and in the treatment of multidrug resistance.
2. Infections caused by Mycobacterium avium complex (MAC): Rifabutin may be used to treat infections caused by Mycobacterium avium complex, especially in patients with HIV infection who develop bacterial infection as a result of immunosuppression.
3. Prevention of infections in patients with HIV infection: Rifabutin can sometimes be prescribed to prevent infections, especially in patients with HIV infection and low immunity.
4. Tuberculosis prophylaxis: In rare cases, rifabutin may be used to prevent tuberculosis in people at increased risk of developing the disease, such as patients with HIV infection or patients receiving immunosuppressive therapy.

Release form

Oral capsules: The most common form of rifabutin is capsules, which are taken orally. Capsules usually contain 150 mg of the active substance.

Pharmacodynamics

The pharmacodynamics of rifabutin is related to its ability to inhibit bacterial DNA synthesis by blocking the action of bacterial RNA polymerase. This leads to disruption of bacterial growth and reproduction, which makes them more vulnerable to the action of the body's immune system and antibiotics.

Pharmacokinetics

1. Absorption: Rifabutin has good and rapid absorption from the gastrointestinal tract after oral administration. It is usually taken orally.
2. Metabolism: Rifabutin is extensively metabolized in the liver by cytochrome P450. The main metabolites are 25-O-desmethylrifabutin and 31-hydroxyrifabutin.
3. Elimination: Metabolites of rifabutin are eliminated mainly with bile, and a small amount is excreted with urine.
4. Half-life: The half-life of rifabutin is approximately 45 hours, which means that its elimination time from the body is long.
5. Protein binding: Rifabutinbinds strongly to plasma proteins, mainly to albumin.
6. Interactions: Rifabutin may affect the metabolism of other drugs through the induction of cytochrome P450 enzymes, which may lead to a decrease in their effectiveness. It should also be taken into account that some drugs may affect the metabolism of rifabutin and increase its concentration in the blood.

Dosing and administration

• For adults for prophylaxis of MAC infection, the usual dose is 300 mg per day, taken once daily.
• For the treatment of MAC infection, the dose may be increased to 450-600 mg per day depending on the clinical picture and treatment regimen, including combination with other drugs.
• In the context of tuberculosis treatment, the dosage and duration of the course will be adapted depending on the recommendations of the treating physician and the treatment regimen used.

Rifabutin should be taken orally, regardless of food intake. However, taking with food may help to reduce the risk of gastrointestinal side effects.

Use Rifabutin during pregnancy

The use of rifabutin during pregnancy should be prescribed only if absolutely necessary and under the supervision of a doctor. During pregnancy, the doctor's instructions should be strictly followed and the potential risks and benefits of the drug should be discussed.

Rifabutin can pass through the placenta and adversely affect fetal development. For women who are taking rifabutin and are planning a pregnancy or are already pregnant, close medical supervision and regular medical consultations are necessary to assess the possible risks and benefits of treatment.

Contraindications

1. Hypersensitivity: People with known hypersensitivity to rifabutin or any other ingredient of the drug should not use it.
2. Liver disease: The use of rifabutin may be undesirable in patients with severe liver disease such as cirrhosis or hepatitis.
3. Leukopenia: Rifabutin may cause leukopenia (decreased white blood cell count), so it should be used with caution in patients with this condition.
4. Hyperbilirubinemia: The use of rifabutin may cause an increase in blood bilirubin levels and should therefore be used with caution in patients with this condition.
5. Pregnancyand breastfeeding: The use of rifabutin during pregnancy or breastfeeding should be used only when strictly necessary and under medical supervision.
6. Pediatric age: Data on the safety and efficacy of rifabutin in children are limited, therefore its use in children should be supervised by a physician.
7. Interactions with other medicines: Rifabutin may interact with various medicines, including antiretrovirals and antibiotics, which may increase or decrease their effectiveness.

Side effects Rifabutin

Side effects of rifabutin may include:

• Diarrhea.
• Kidney failure.
• Changes in the liver.
• Increased liver enzyme levels.
• Hyperpigmentation (skin discoloration).
• Skin reactions such as hives or itching.
• Neutropenia (a decrease in the number of neutrophils in the blood).

Overdose

There is limited information on rifabutin overdose in the literature; however, dose-dependent side effects such as hyperpigmentation of the skin and eyewear have been found with oral administration of rifabutin.

In case of rifabutin overdose, medical attention should be sought. Symptomatic treatment and maintenance of the functions of organs and systems of the body may be required.

Interactions with other drugs

1. Inhibitors or inducers of liver enzymes: Rifabutin is metabolized in the liver with the participation of cytochrome P450 enzymes. Therefore, drugs that are strong inhibitors or inducers of these enzymes may alter its concentration in the blood. For example, proton pump inhibitors (e.g., omeprazole) or azole antimycotics may increase rifabutin blood levels, while enzyme inducers (e.g., rifampin) may decrease its concentration.
2. Antituberculosis drugs: Rifabutin is often used in combination with other antituberculosis drugs. Interactions between rifabutin and other TB drugs (e.g. Isoniazid, rifampin) may alter treatment efficacy and require careful monitoring.
3. Antiretroviral drugs: Rifabutin may interact with some antiviral drugs used to treat HIV, such as ritonavir and other protease inhibitors. This may lead to changes in the concentration of both rifabutin and antiviral drugs.
4. Flu and cold medications: Medications containing phenylephrine, caffeine, or pseudoephedrine may increase the effects of rifabutin and increase blood pressure.
5. Drugs for thetreatment of psychiatric disorders: Drugs such as phenothiazines (e.g. Chlorpromazine) may increase rifabutin blood concentrations.