Rifamycin Delayed-Release Tablets - An Overview

Overview:

Rifamycin is used to treat diarrhea, especially traveler's diarrhea (stomach or intestinal infection due to poor hygiene and sanitation), brought on by the bacteria Escherichia coli (E. coli). It works by inhibiting bacterial growth. Only bacterial infections are treated by this medication; it does not treat viral infections, such as the flu or the common cold. Antibiotics like Rifamycin can become less effective against subsequent infections if they are overused or misused. You should avoid using Rifamycin if you have bloody diarrhea or a fever, as these symptoms could be signs of a more serious infection. The United States Food and Drug Administration (US FDA) approved the use of Rifamycin in 2018.

Drug Group:

Rifamycin delayed-release tablets belong to the group of antibiotics.

Dosage:

Rifamycin delayed-release tablets is a yellow-brown, ellipsoidal film-coated delayed-release tablet, debossed on one side with "SV2". Each delayed-release tablet contains 194 mg (milligrams) of Rifamycin.

The recommended dose for Rifamycin delayed-release tablet is 388 mg (milligrams), two tablets to be taken orally twice daily in the morning and evening for a period of three days. The dose should be taken with six to eight ounces of liquid or a glass of liquid. The patient should not take Rifamycin with alcohol. Food is also not necessary, but it can be taken with or without food.

For Patients:

Indication:

Rifamycin delayed-release tablets are recommended for the treatment of adult travelers' diarrhea brought on by non-invasive Escherichia coli strains.

Contraindication:

Patients with a history of Rifamycin hypersensitivity, hypersensitivity to other Rifamycin-class antibiotics (such as Rifaximin), or hypersensitivity to any of the ingredients in Rifamycin delayed-release tablets should not use this medication.

Limitations:

Patients who have bloody stools, diarrhea with fever, or infections from bacteria other than noninvasive types of Escherichia coli (E. coli) are not advised to take Rifamycin delayed-release tablets. This medicine should only be used to treat or prevent infections that are confirmed or highly suspected to be bacterial in origin in order to help prevent the development of drug-resistant bacteria and maintain the efficacy of Rifamycin delayed-release tablets and other antibacterial drugs. Rifamycin delayed-release tablets must be taken precisely as directed by a doctor. Missing doses or not finishing the entire course of treatment can decrease the efficacy of the current therapy and raise the possibility that bacteria will become resistant, which could make it more difficult to treat infections in the future with this antibiotic or other antibacterial medications.

Why Is Rifamycin Delayed-Release Tablet Used for Travelers Diarrhea?

Traveler's diarrhea is an illness that manifests itself 10 days after visiting a place of poor sanitation, with the mode of entry being through the ingestion of contaminated food or water. The primary agent causing this is Enterotoxigenic Escherichia coli (ETEC), but Shigella, Salmonella, Campylobacter jejuni, norovirus, rotavirus, and the parasite Giardia intestinalis are also considered agents. The symptoms include abdominal cramps, bloating, fever, vomiting, sudden diarrhea, and exhaustion. It usually resolves itself, but it can lead to complications, such as dehydration, under extreme conditions. Higher temperatures without proper hygiene, polluted water, and poor food preparation and handling increase the risk. Future attacks cannot be prevented, but in milder cases, the cause is often not identified. Food handling education can significantly decrease the incidence.

Rifamycin delayed-release tablets are used in the treatment of traveler's diarrhea due to the Escherichia coli bacterium only and not that are caused due to other pathogens. It inhibits the multiplication of bacteria while killing them. However, Rifamycin fails to act on viral infections, such as the flu and the common cold.

How Should Rifamycin Delayed-Release Tablets Be Used?

Rifamycin delayed-release tablet is designed to be released in the intestine, wherein the drug acts best. It can be used twice a day, in the morning and evening, for a period of three days. Rifamycin may be taken with or without food but taken at consistent times every day. Always follow your prescription instructions. Take this medication exactly as prescribed; do not take more or less of it, and do not take it more often than directed by your physician. Swallow the tablets whole with six to eight ounces of liquid; do not crush, chew, or split them. Most people start feeling better right away, but full recovery takes time. However, if your symptoms are not improving within 48 hours or are getting worse, or you develop a fever or bloody diarrhea, you must immediately call your doctor. It is very important to take the full course of prescribed medication even after feeling better and to not stop or skip prescribed doses, as this can result in incomplete recovery and increased resistance to antibiotics.

What Are the Side Effects of Rifamycin Delayed-Release Tablets?

You should notify your physician or other healthcare practitioner right away if you have any of the following severe adverse effects:

• Skin rash, itching, hives, or swelling of the face, lips, or tongue are examples of allergic reactions.

• Watery or bloody diarrhea.

• A fever.

There may be additional adverse effects that usually do not need to be treated right away, but you should still talk to your doctor if they continue or start to annoy you. These include:

• Constipation.

• A headache.

• Pain in the stomach.

• Upset stomach.

What Are the Things to Inform the Doctor Before Taking Rifamycin Delayed-Release Tablets?

• Before taking Rifamycin delayed-release tablets, inform your doctor and pharmacist if you are allergic to Rifamycin, Rifaximin, Rifabutin, Rifampin, Rifapentine, or any other medications or if you are allergic to any of the ingredients in Rifamycin tablets.

• Additionally, tell your doctor and pharmacist about all other prescription and nonprescription medications, vitamins, and nutritional supplements you are currently taking or plan to take, as your doctor may need to adjust your medication doses or monitor you for potential side effects.

• It is also important to inform your doctor if you have a history of other medical conditions.

• If you are pregnant, or if you plan to become pregnant or are breastfeeding a baby, your doctor will likely change your therapy. Seek medical help immediately if you become pregnant during the use of Rifamycin.

Missed Dose:

Take the missed dose as soon as you remember. However, if it is nearly time for the next dose, skip the missed one and continue with your regular dosage schedule. Do not take two doses to replace the dose that was missed.

Overdose:

In case of overdosing, contact the emergency medical services right away.

Dietary Instructions:

Rifamycin delayed-release tablets should not be taken with alcohol. Food is not a restriction, and the tablets can be taken with or without food as a personal choice.

For Doctors:

Clinical Pharmacology

• Chemical Name: Sodium (2S,12Z,14E,16S,17S,18R,19R,20R,21S,22R,23S,24E)-21-(acetyloxy)-6,9,17,19-tetrahydroxy-23­ methoxy2,4,12,16,18,20,22-heptamethyl-1,11-dioxo-1,2-dihydro-2,7 (epoxypentadeca[1,11,13]trienimino)naphtho[2,1-b]furan-5-olate.

• Molecular Formula: C37H46NNaO12.

• Molecular Weight: 720 g/mol (grams per mol).

• Inactive Ingredients: Triethylcitrate, titanium dioxide, polyethylene glycol 6000, colloidal silicon dioxide, ascorbic acid, yellow ferric oxide, lecithin, talc, methacrylic acid, d methyl methacrylate copolymer (1:2), mannitol, ammonia methacrylate copolymer (Type B), magnesium stearate, and glyceryl distearate.

• Solubility: Dissolves readily in anhydrous ethanol and is soluble in water.

• Appearance: Slightly granular or fine. Ellipsoidal in shape and yellow in color.

Mechanism of Action:

Rifamycin, an antibiotic belonging to the ansamycin class, prevents a crucial stage in DNA (deoxyribonucleic acid) transcription by inhibiting the beta component of bacterial DNA-dependent RNA (ribonucleic acid) polymerase. By stopping bacterial protein synthesis, this mechanism effectively stops bacteria from growing.

Resistance:

Mutations in the beta subunit of RNA polymerase cause resistance to Rifamycin. At concentrations of 4x to 16x, the minimum inhibitory concentration (MIC), the spontaneous mutation frequency to rifamycin resistance in E. coli varies from 10⁻⁶ to 10⁻¹⁰, and this rate is constant irrespective of the Rifamycin concentration. In vitro and during treatment, exposure to Rifamycin has been linked to higher MIC values. There has also been evidence of cross-resistance between Rifamycin and other ansamycins.

Antibiotic Resistance:

The majority of Escherichia coli isolates, including enterotoxigenic and enteroaggregative bacteria, have been shown to be susceptible to Rifamycin in both in vitro and clinical traveler's diarrhea trials.

Pharmacodynamics:

For Rifamycin delayed-release tablets, neither the time course of the pharmacodynamic response nor the exposure-response connections are yet understood.

Pharmacokinetics:

• Plasma Concentrations: The maximum level of Rifamycin in the blood was 8.72 ng/mL (nanogram per milliliter) six hours after the last dose in healthy people who took the recommended dosage of 388 mg of Rifamycin twice daily for three days. The majority of the rifamycin levels (67 percent) were below two ng/mL (nanogram per milliliter) at this time, making them too low to be precisely assessed.

• Absorption: When taken orally at the indicated dosage, Rifamycin delayed-release tablets show minimal systemic absorption. Based on total urine excretion, bioavailability in fasting conditions was calculated to be less than 0.1 percent.

• Food Effect: A study that compared fed and fasted states (meal of about 1,000 kilocalories with 500 kilocalories from fat) discovered that food intake reduced systemic exposure to rifamycin. It is not anticipated that this decrease will affect clinical efficacy.

• Distribution: In vitro, Rifamycin binds to plasma proteins around 80% of the time, mostly to albumin, and its binding is inversely proportional to its concentration.

• Excretion: Rifamycin delayed-release tablets taken orally have an unclear plasma half-life at this time.

• Metabolism: Rifamycin was not shown to be metabolized by cytochrome P450 (CYP) in vitro.

Drug Interaction:

The effects of Rifamycin on other medications in the body have not been investigated in clinical trials.

Non-Clinical Toxicology:

• Carcinogenesis and Fertility: Studies have not been conducted in animals with Rifamycin.

• Mutagenesis: A number of laboratory experiments, such as the mouse lymphoma cell mutation assay, the mouse bone marrow micronucleus assay, and the bacterial reverse mutation assay, did not reveal that Rifamycin was genotoxic.

What Are the Warnings and Precautions for Rifamycin Delayed-Release Tablets?

• Clostridium Difficile-Associated Diarrhea: Nearly all antibacterial medications can cause Clostridium difficile-associated diarrhea (CDAD), which can vary from moderate diarrhea to life-threatening colitis. The overgrowth of C. difficile is encouraged by the disruption of normal gut flora caused by antibiotic use. Toxins A and B, which are produced by the bacteria and contribute to CDAD, might have serious consequences, such as treatment resistance and even the need for a colectomy. Any patient who experiences diarrhea after taking antibiotics should be evaluated for CDAD; since it can happen up to two months later, a complete medical history is crucial. Non-C. difficile-directed medications should be stopped if CDAD is suspected or proven. Treatment options include protein supplements, fluid and electrolyte replacement, specialized C. difficile medicines, and/or surgical examination.

• Development of Drug-Resistant Bacteria: Prescribing Rifamycin delayed-release tablets in the absence of a confirmed or strongly suspected bacterial infection or for prophylactic purposes is unlikely to benefit the patient and may contribute to the development of drug-resistant bacteria.

• Risk of Persistent or Worsening Diarrhea Complicated by Fever or Bloody Stool: It has not been demonstrated that Rifamycin delayed-release tablets work well for patients whose diarrhea is accompanied by fever or bloody stools. In these instances, a prolonged time to last unformed stool (TLUS) was the outcome of Rifamycin delayed-release tablets. It has not been shown to be effective in treating travelers' diarrhea brought on by infections other than E. coli. As a result, patients who have diarrhea that is accompanied by fever or bloody stools or that is brought on by pathogens other than noninvasive types of E. coli, should not use Rifamycin delayed-release tablets. Rifamycin delayed-release tablets should be stopped, and alternate antimicrobial treatment should be explored if diarrhea gets worse or lasts longer than 48 hours.

Use in Specific Population:

• Pregnancy: There is currently no information on the usage of Rifamycin delayed-release tablets in pregnant women to determine the risks of miscarriage, birth deformities, or other issues for either the mother or the unborn child. Rifamycin delayed-release tablets are rarely absorbed by the body when taken orally. Hence, the fetus is unlikely to be impacted by the medication.

• Lactation: No information is available regarding whether Rifamycin delayed-release tablets enter human milk, how it impacts milk supply, or how it affects a breastfed infant. Rifamycin delayed-release tablets are rarely absorbed by the body when taken orally, thus it is anticipated that very little of it will end up in breast milk. When choosing whether to use Rifamycin delayed-release tablets, the advantages of nursing should be weighed against the mother's need for the drug, any possible side effects on the unborn child, and the mother's health.

• Pediatric Population: The efficacy and safety of Rifamycin delayed-release tablets in treating travelers' diarrhea in children under the age of eighteen have not been determined.

• Geriatric Population: There were not enough people 65 and older in clinical trials of Rifamycin delayed-release tablets for travelers' diarrhea to ascertain whether their reactions differed from those of younger patients. Other clinical experience, however, has not found any appreciable variations in the responses of younger and older patients.

• Renal Impairment: No research has been done on the pharmacokinetics of Rifamycin delayed-release tablets in patients with renal impairment. Renal impairment is not predicted to have a clinically significant effect on Rifamycin systemic exposure, and no dose adjustment is required because of the low systemic exposure of Rifamycin and the negligible involvement of renal excretion in its removal.

• Liver Impairment: There is no research on the pharmacokinetics of Rifamycin delayed-release tablets in hepatic impairment patients. Hepatic impairment is unlikely to have a substantial impact on Rifamycin systemic exposure because of its low level, and no dose change is advised.

Clinical Trials:

In a research, people received 388 mg of the medication twice a day for three days to examine the efficacy of Rifamycin delayed-release tablets, a treatment for traveler's diarrhea. The primary trial (Trial 1) was held in Guatemala and Mexico, while the second trial (Trial 2) was held in India, Guatemala, and Ecuador. The purpose of the studies was to evaluate the efficacy in treating diarrhea brought on by E. coli, which was the most prevalent pathogen in both trials. Although patients with fever or bloody stools were eliminated from both trials, 18 patients in Trial 2 continued to have both conditions at the beginning of treatment. Before and after therapy, stool samples were taken to look for illnesses. Stool samples were taken both before and after therapy to examine the pathogens. The time it took for patients to stop having soft or watery stools served as the primary indicator of the medication’s efficacy. Having no loose stools after 48 hours or no more than two soft stools with little symptoms in a 24-hour period was considered a clinical cure.

According to the study, when compared to patients who received a placebo, those who received Rifamycin delayed-release tablets experienced diarrhea for a significantly shorter period of time. Furthermore, compared to the placebo group, more patients receiving Rifamycin delayed-release tablets recovered completely. Trial 2 supported the result of Trial 1.