amoxicillin/omeprazole/rifabutin

Action and Spectrum

Actions and Spectrum 

By inhibiting the formation of the bacterial cell wall, amoxicillin eliminates the germs that are causing the infection. 

omeprazole lessens the stomach’s production of acid, which helps to lessen the irritation of the stomach lining that may be brought on by an infection with H. pylori. 

rifabutin functions by preventing bacteria from synthesising RNA, which ultimately results in bacterial death. 

These medications range of activity can be characterised as follows: 

Gram-positive and some gram-negative bacteria are among the many types of bacteria that amoxicillin is effective against. 

Since omeprazole is not an antibiotic, it has a limited range of antibacterial activity. Gram-positive and some gram-negative bacteria are both susceptible to the antibiotic rifabutin. 

Drug Interaction

Adverse Reaction

Frequency defined  

>10% 

For rifabutin 

Leukopenia (17%) 

Rash (11%) 

Discoloration of urine (30%) 

Neutropenia (25%) 

1-10% 

For omeprazole 

Constipation (1.5%) 

Asthenia (1.3%) 

Back pain (1.1%) 

Acid regurgitation (1.9%) 

Dizziness (1.5%) 

Rash (1.5%) 

Cough (1.1%) 

Upper respiratory infection (1.9%) 

For rifabutin 

Nausea/vomiting (3%) 

Anorexia (2%) 

Thrombocytopenia (5%) 

Headache (3%) 

Anemia 

Flatulence (2%) 

Eructation (3%) 

Abdominal pain (4%) 

Myalgia 

Diarrhea (3%) 

Frequency not defined 

For amoxicillin 

nausea, vomiting 

Rash 

Anemia 

Candidiasis  

Headache 

Anaphylaxis 

Diarrhea 

For omeprazole 

Hepatotoxicity (rare) 

Pancreatitis (rare) 

Rhabdomyolysis 

Interstitial nephritis (rare) 

Toxic epidermal necrolysis (rare) 

Hip fracture 

Fracture of bone, osteoporosis-related 

Post marketing reports 

For acute tubulointerstitial nephritis 

Severe cutaneous adverse reactions, including toxic epidermal necrolysis (TEN) and Stevens-Johnson syndrome (SJS) 

For amoxicillin 

Central nervous system:  

Confusion, Hyperactivity, agitation, anxiety, insomnia, aseptic meningitis, behavioral changes, convulsions 

Black Box Warning

Black Box Warning 

The combination of amoxicillin/omeprazole/ rifabutin does not have the black box warning. 

Contraindication / Caution

Contraindication/Caution: 

• This medication should not be taken by anyone who is known to be allergic or hypersensitive to any of the individual medications in this combination. 
• While taking this medication, patients with liver or kidney disease may need to adjust their dosage or be closely monitored. 
• The likelihood of getting diarrhoea linked to Clostridium difficile can rise with antibiotic use.  
• While taking omeprazole, patients with bleeding disorders may need to have their blood clotting function monitored. 

Pregnancy / Lactation

Pregnancy warnings:     

Pregnancy category: N/A 

Lactation: Excretion into human milk is unknown  

Pregnancy Categories:         

Category A: Studies that were well-controlled and met expectations revealed no risk to the fetus in either the first or second trimester. 

Category B: There were lack of studies on pregnant women and no evidence of risk to the foetus in animal experiments.   

Category C: there was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women.    

Category D: adequate data available with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits.   

Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women.    

Category N: There is no data available for the drug under this category

Pharmacology

Pharmacology 

amoxicillin is an antibiotic like penicillin that kills bacteria by preventing the formation of their cell walls. 

A proton pump inhibitor (PPI), omeprazole lowers the quantity of stomach acid generated.  

The antibiotic rifabutin is a member of the rifamycin medication class. It functions by preventing bacteria from synthesizing RNA, which ultimately results in bacterial death. 

Pharmacodynamics 

amoxicillin inhibits the formation of peptidoglycan by attaching to the penicillin-binding proteins (PBPs) found in the bacterial cell wall, which has a bactericidal effect. 

omeprazole is a proton pump inhibitor (PPI) that reduces the amount of acid produced into the stomach by permanently blocking the hydrogen-potassium ATPase enzyme system in the parietal cells of the stomach. 

rifabutin is a bactericidal antibiotic that kills bacteria by preventing their ability to synthesize RNA. By attaching to the beta subunit of bacterial RNA polymerase, it prevents RNA synthesis and has a bactericidal effect. 

Pharmacokinetics 

Absorption   

amoxicillin has a bioavailability of about 80 to 90% following oral administration and is easily absorbed. It spreads quickly and evenly throughout the body, with the kidneys, liver and urinary system containing the highest quantities. 

omeprazole is supplied as an enteric-coated tablet or capsule since it is acid-labile and needs to be protected from stomach deterioration. It is quickly absorbed from the small intestine, and around 50% of it is bioavailable. Food slows down and reduces the absorption. 

Following oral administration, rifabutin is efficiently absorbed, with a 20% bioavailability. It is advised to take it with food to boost its bioavailability. 

Distribution 

amoxicillin is widely dispersed throughout the body, including the lungs, bones, and cerebrospinal fluid, with a volume of distribution of about 0.3 L/kg. 

omeprazole has a volume of distribution of about 0.3 to 0.5 L/kg and is well bound to plasma proteins. 

rifabutin is broadly distributed throughout the body and has a volume of distribution of roughly 0.7 to 1 L/kg. 

Metabolism 

amoxicillin undergoes very little hepatic metabolism and is mostly eliminated unaltered in the urine. 

The liver uses the cytochrome P450 (CYP) system to extensively metabolize omeprazole. 5-hydroxyomeprazole, the main metabolite, is inert. 

The CYP3A4 enzyme system is used by the liver to extensively metabolize rifabutin. 

Elimination and excretion 

amoxicillin is excreted unchanged in the urine, and after six hours of treatment, 60 to 70% of the dose is gone. 

With the remaining being removed in the feces, omeprazole is primarily eliminated in the urine as inactive metabolites. 

The majority of rifabutin’s metabolites are expelled in the feces together with the remaining amount in the urine. 

Adminstartion

Administration:  

To improve rifabutin absorption, medications are often given twice daily with food, about 12 hours apart. 

Instead of crushing or chewing, it is best to swallow them whole. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: amoxicillin/omeprazole/rifabutin 

Why do we use amoxicillin/omeprazole/rifabutin? 

In patients with gastritis or peptic ulcer disease, Helicobacter pylori infection is primarily treated with the combination of amoxicillin/omeprazole/rifabutin.  

Eliminating the bacteria H. pylori can help prevent recurrent ulcers and reduce the risk of gastric cancer.