Clarithromycin Tablets

Below is a detailed article about clarithromycin (sometimes spelled “clarithomycine”) tablets. I did not find reliable public information confirming a product called “Zencus Pharma clarithomycine,” so I’ll first cover the general drug, and then discuss possible issues / cautions (and how to check whether “Zencus Pharma” is a valid manufacturer).

Introduction

Clarithromycin is an antibiotic in the macrolide class. It is used to treat various bacterial infections by inhibiting bacterial protein synthesis.

It is not effective against viral infections (e.g. colds, flu), and should only be used when a bacterial cause is known or strongly suspected. 

The drug is sometimes seen under brand names like Biaxin (in some countries) and also under generic forms.

Mechanism of Action & Pharmacology

• Clarithromycin works by binding to the 50S ribosomal subunit in bacteria, inhibiting the translocation step of protein synthesis. This prevents the bacteria from making proteins, thus inhibiting their growth (or killing them, depending on concentration).
• It is a semi-synthetic derivative of erythromycin, designed to have improved acid stability and better tissue penetration.
• It is metabolized in part to an active metabolite (14-OH clarithromycin) which also contributes to antimicrobial effect.
• Clarithromycin also inhibits the hepatic enzyme CYP3A4 and P-glycoprotein, which leads to many drug–drug interactions.

Indications & Uses

Clarithromycin is used in clinical practice for a number of infections caused by susceptible bacteria. Some of the common uses include:

• Respiratory tract infections: community-acquired pneumonia, bronchitis exacerbations, sinusitis
• Skin and soft tissue infections
• Ear, nose, throat infections (e.g. pharyngitis, tonsillitis)
• As part of triple therapy to eradicate Helicobacter pylori (the organism associated with peptic ulcers) in combination with other drugs (e.g. amoxicillin, proton pump inhibitors)
• Infections by Mycobacterium avium complex (MAC) especially in immunocompromised patients

It should be emphasized that clarithromycin (and indeed all antibiotics) should be used only when bacterial infection is present or strongly suspected, in order to limit antibiotic resistance.

Contraindications & Precautions

Contraindications

Clarithromycin should not be used in:

• Patients with known hypersensitivity to clarithromycin, erythromycin, or other macrolide antibiotics
• Concomitant use with cisapride or pimozide, due to risk of serious cardiac arrhythmias (QT prolongation, torsades de pointes)
• Patients with history of cholestatic jaundice or hepatic dysfunction associated with prior use of clarithromycin
• Concomitant use with colchicine in patients with renal or hepatic impairment (due to risk of colchicine toxicity)
• Concomitant use with lovastatin or simvastatin (because clarithromycin inhibits CYP3A4, increasing risk of statin toxicity)
• Concomitant use with ergotamine or dihydroergotamine (risk of ergot toxicity)
• Concomitant use with lurasidone (due to drug interaction risks)

Warnings / Precautions

• QT prolongation / arrhythmias: Clarithromycin can prolong the QT interval; risk is increased with other QT-prolonging drugs or in patients with electrolyte abnormalities.

• Hepatotoxicity: Rare but serious liver injury, including cholestatic hepatitis, hepatic failure has been reported. Monitor patients, especially if preexisting liver disease.

• Clostridioides difficile infection: As with many broad-spectrum antibiotics, there is a risk of C. difficile–associated diarrhea, which can be severe.

• Allergic reactions / severe cutaneous reactions: Stevens-Johnson syndrome, toxic epidermal necrolysis, DRESS, etc. Discontinue if signs appear.

• Myasthenia gravis: May exacerbate this neuromuscular disease.

• Mortality risk in patients with coronary artery disease: Some observational studies suggest increased long-term mortality in patients with coronary disease after clarithromycin therapy; this is a reported risk and should be weighed in decision-making.

• Drug resistance development: If misused (incomplete courses, use for viral infections), bacteria may become resistant.

In pregnant or lactating women, clarithromycin should be used only if clearly needed; the risks vs benefits must be weighed.