Althrocin
✅ Treats Bacterial Infections Broadly
✅ Allergy-Friendly Antibiotic Option
✅ Prevents Strep Infections
✅ Easy Dosage Administration
Althrocin contains Erythromycin
✓ Medically reviewed by Morgan Ellis — Pharmacy Researcher · 8 years experience · Last reviewed: May 2026
⚡ Quick Answer — What is Althrocin?
Althrocin is an erythromycin estolate tablet (250 mg / 500 mg, Alembic) — the original macrolide. Used for streptococcal pharyngitis (penicillin-allergic), atypical pneumonia, chlamydia in pregnancy, and as a low-dose prokinetic for gastroparesis. Strong CYP3A4 inhibitor.
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How Althrocin works
Althrocin contains Erythromycin estolate, a macrolide antibiotic that binds the 50S bacterial ribosomal subunit and blocks peptide-chain elongation, arresting bacterial protein synthesis. Macrolides are bacteriostatic at standard doses but bactericidal at higher concentrations against susceptible organisms. Spectrum includes Streptococcus species (including some penicillin-resistant pneumococci), Mycoplasma pneumoniae, Chlamydia trachomatis and pneumoniae, Legionella, Bordetella, and Helicobacter pylori. Activity against staphylococci is unreliable due to widespread macrolide resistance, and most Enterobacteriaceae are intrinsically resistant.
Erythromycin is the original macrolide. It is rarely first-line today because of poor GI tolerability (it is itself a motilin-receptor agonist — useful as a prokinetic but causes nausea / cramps), strong CYP3A4 inhibition, and dosing inconvenience.
Indications & dosing
| Indication | Dose | Duration |
|---|---|---|
| CAP / atypical pneumonia | 500 mg four times daily | 7–14 days |
| Streptococcal pharyngitis (penicillin-allergic) | 500 mg four times daily | 10 days |
| Chlamydia trachomatis (pregnancy alternative) | 500 mg four times daily | 7 days |
| Gastroparesis (off-label prokinetic) | 125–250 mg three times daily before meals | As clinically indicated |
All macrolides can prolong the QT interval and trigger torsades de pointes — particularly in patients with congenital long QT, electrolyte disturbance (low K+ / Mg2+), bradycardia, concurrent QT-prolonging medications (azoles, fluoroquinolones, citalopram, ondansetron, certain antipsychotics, some antiarrhythmics) or significant cardiac disease. Azithromycin received an FDA black-box update in 2013 after observational data linked it to a small absolute increase in cardiovascular death in patients with elevated baseline cardiac risk. Patients with stable cardiovascular disease can usually receive a macrolide safely; high-risk patients — known long-QT, recent MI, advanced heart failure — may need an alternative class.
Side effects
- GI: nausea, abdominal cramps, diarrhoea (worst with erythromycin — affects up to 30% of patients due to motilin agonism). Azithromycin / clarithromycin / roxithromycin are better tolerated.
- Taste disturbance / metallic taste: common with clarithromycin; bothersome but reversible.
- Hepatotoxicity: cholestatic hepatitis (rare with azithromycin; more common with erythromycin estolate). Watch for jaundice, RUQ pain.
- QT prolongation / torsades: rare absolute risk but real (see warning above).
- Hearing impairment: reversible ototoxicity reported with high-dose macrolides, especially in renal impairment.
- Allergic reactions: rash, urticaria, very rarely Stevens-Johnson / TEN.
Contraindications
- Known macrolide hypersensitivity.
- Concurrent use with strong QT-prolonging drugs (especially Class IA / III antiarrhythmics).
- Severe hepatic impairment (especially erythromycin estolate).
- Concurrent ergot alkaloids (vasospasm risk with strong CYP3A4 inhibitors — clarithromycin/erythromycin).
- Concurrent terfenadine / astemizole / cisapride / pimozide / lovastatin / simvastatin (with strong CYP3A4 inhibitors only).
Drug interactions
| Drug | Effect | Action |
|---|---|---|
| Warfarin | INR rise — multiple mechanisms | Check INR 3–5 days in; counsel |
| Statins (simvastatin / lovastatin) | Severe rhabdomyolysis risk with clarithromycin / erythromycin | Hold statin during course (atorvastatin / rosuvastatin / pravastatin / fluvastatin are safer) |
| Calcium-channel blockers (verapamil / diltiazem / amlodipine) | Hypotension / shock with clarithromycin | Avoid combination in elderly |
| Colchicine | Severe colchicine toxicity (especially in renal impairment) | Hold colchicine or use alternative antibiotic |
| Carbamazepine / phenytoin | Increased levels via CYP3A4 inhibition (clari/eryth) | Monitor levels |
| Ergot alkaloids | Severe peripheral vasospasm (clari/eryth) | Absolute contraindication |
| Digoxin | Raises digoxin levels via gut-flora effect | Monitor digoxin level |
| Quetiapine / pimozide | QT prolongation | Avoid combination |
Pregnancy & Breastfeeding
Macrolides are FDA category B. Erythromycin and azithromycin are widely used in pregnancy. Clarithromycin is category C — reserve for situations where benefit outweighs risk; alternatives (azithromycin, amoxicillin) are preferred. For chlamydia in pregnancy, azithromycin 1 g single dose is first-line. All macrolides cross into breast milk in small amounts; compatible with breastfeeding.
Storage
Store below 25 °C, away from direct sunlight and moisture. Keep in original packaging. Keep out of reach of children. Discard any unused tablets after the printed expiry date — degraded antibiotics can lose potency or release breakdown products.
This medicine is only effective against bacterial infections. Do not use it for viral illnesses (common cold, most sore throats, flu, COVID-19), do not stop early when you feel better, and do not save leftovers for future infections. Misuse drives drug-resistant bacteria like MRSA, ESBL, and CRE — the WHO ranks antimicrobial resistance among the top 10 global public-health threats.
Frequently Asked Questions
How fast does Althrocin work?
Most patients begin to feel better within 48–72 hours. Azithromycin’s long intracellular half-life means treatment continues for ~7 days even after a 5-day course ends — do not assume the course is too short.
Should I take it with food?
Erythromycin base / stearate is best taken on an empty stomach (1 hour before food). Erythromycin estolate / ethylsuccinate can be taken with food.
Can I take it if I have heart disease?
Stable cardiovascular disease is not an absolute contraindication. Patients with congenital long-QT, recent acute coronary events, advanced heart failure, or concurrent QT-prolonging medications should discuss alternatives with their prescriber.
Why does my doctor avoid clarithromycin with my statin?
Clarithromycin is a strong CYP3A4 inhibitor and dramatically raises levels of simvastatin and lovastatin — risk of severe muscle injury (rhabdomyolysis) and acute kidney injury. The statin should be paused for the antibiotic course or switched to a non-CYP3A4 statin (rosuvastatin, pravastatin).
What if I miss a dose?
Take it as soon as you remember. If you are within a few hours of the next dose, skip and resume. Do not double up.
Does Althrocin interact with my contraceptive pill?
Modern evidence does not support clinically important reductions in pill efficacy. Continue your usual schedule. Use additional protection if you experience vomiting or diarrhoea.
Can I drink alcohol?
There is no direct interaction. Heavy drinking increases nausea and slows immune recovery — moderate use is acceptable.
Will Althrocin cover MRSA?
No — most MRSA strains are macrolide-resistant via efflux pumps and target modifications. For MRSA, use clindamycin / doxycycline / TMP-SMX / linezolid based on local susceptibility data.
Why did my doctor give me a single 1 g dose for chlamydia?
Azithromycin 1 g single oral dose achieves curative tissue levels for >7 days against Chlamydia trachomatis. Confirmed treatment failure rates are low (~5%); test of cure is recommended at 3 months because re-infection is common.
Can I use this for a viral cold?
No. Macrolides have no antiviral activity. Using them for the common cold or simple flu provides no benefit, accelerates resistance, and exposes you to QT and GI side effects unnecessarily.
Other Antibiotics & Anti-Infective Medications
- Azee (Azithromycin) — short-course macrolide alternative
- Claribid (Clarithromycin) — H. pylori, atypical pneumonia
- Doxt (Doxycycline) — atypical pneumonia / STIs
- Augmentin (Amoxicillin + Clavulanic acid) — beta-lactam alternative
- Levomac (Levofloxacin) — respiratory fluoroquinolone
More options in Traveller’s Diarrhea Treatment
Ranked by recent MedsBase order volume — what other customers in this category are picking.
| Strength | 250 mg, 500 mg |
|---|---|
| Quantity | 30 Tablet/s, 60 Tablet/s, 90 Tablet/s |
| Pharma Form | Tablet/s |
| Manufacturer | Alembic Pharma |
| Treatment | Bacterial infections |
| Generic Brand | Erythromycin |
Althrocin
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Althrocin
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