Erythroprim
1. Disclaimer
This commentary is provided for general educational and informational purposes only and is not a substitute for the official package leaflet, prescribing information, or professional medical advice. Drug formulations, approved indications, warnings, and availability may change, and the information below should therefore be interpreted in the context of the product information available for the specific Erythroprim presentation.
We do not guarantee the accuracy, currency or completeness of information regarding medications or medical products, and official sources should be verified before making any decisions. Readers are responsible for independently verifying the information before relying on it.
Erythroprim is an antibacterial combination containing erythromycin and trimethoprim. It should be used only when a bacterial infection is suspected or confirmed to be susceptible to the selected antibacterial therapy. Antibiotic selection should take account of the infection site, likely organisms, local resistance patterns, patient-specific factors, and current prescribing guidance.
2. Summary
Erythroprim is a fixed-dose oral antibacterial combination of erythromycin and trimethoprim. The currently listed Egyptian presentations are a film-coated tablet and a dry oral suspension. Publicly available Egyptian product information identifies Misr as the manufacturer.
The combination brings together two antibacterial mechanisms: erythromycin inhibits bacterial protein synthesis through binding to the 50S ribosomal subunit, while trimethoprim inhibits bacterial dihydrofolate reductase and therefore interferes with tetrahydrofolate-dependent nucleic-acid synthesis.
The original description of Erythroprim as a "broad spectrum antibacterial–antiamoebic" product should be corrected. Erythroprim is antibacterial; it should not be described as an antiamoebic drug. Also, the combination should not automatically be assumed to broaden coverage against "most" Gram-positive and Gram-negative bacteria or to reliably prevent resistance; actual activity depends on the susceptibility of the infecting organism.
3. Brand Name
Erythroprim
Current Egyptian market listings include:
- Erythroprim 20 f.c. tab
- Erythroprim dry susp. 80ml
Both are currently listed with Erythromycin + Trimethoprim as the active combination and Misr as the manufacturer.
4. Category
Therapeutic category: Systemic antibacterial.
Components/classes:
- Erythromycin — macrolide antibacterial.
- Trimethoprim — dihydrofolate-reductase inhibitor antibacterial.
The product is therefore more accurately described as a combination antibacterial containing a macrolide plus trimethoprim, rather than simply a "macrolide antibiotic."
The term antiamoebic should not be used.
5. Active Ingredient
Film-coated tablets
Each tablet is documented in historical Erythroprim product material as containing:
- Erythromycin stearate equivalent to erythromycin base 250 mg
- Trimethoprim 80 mg
Dry suspension
The historical Erythroprim information states that each 5 mL contains:
- Erythromycin ethylsuccinate equivalent to erythromycin base 200 mg
- Trimethoprim 40 mg
These composition figures are consistent with published pharmaceutical literature identifying Erythroprim tablets as containing erythromycin stearate equivalent to 250 mg erythromycin plus 80 mg trimethoprim.
6. Pharmaceutical Form & Strength
Tablets
Film-coated tablets:
Erythromycin base equivalent 250 mg + trimethoprim 80 mg per tablet.
Oral suspension
Dry powder for oral suspension:
Erythromycin base equivalent 200 mg + trimethoprim 40 mg per 5 mL, according to the historical Erythroprim composition information.
Current Egyptian listings continue to identify an 80 mL dry suspension presentation.
7. Manufacturer & Marketing Authorization Holder
Manufacturer: Misr Company for Pharmaceutical Industries, Cairo, Egypt. Historical Erythroprim product material identifies the manufacturer as Misr Co. for Pharmaceutical Industries, and current Egyptian market listings identify Misr as the producer.
Marketing Authorization Holder (MAH): A separately documented current MAH entry could not be independently verified from the accessible public sources reviewed. Therefore, it should not be presented as a separately confirmed entity.
8. Mechanism of Action
Erythromycin
Erythromycin is a macrolide that binds to the 50S subunit of the bacterial ribosome and inhibits bacterial protein synthesis, particularly the translocation step. Its activity may be bacteriostatic or bactericidal depending on organism, concentration, and circumstances.
Trimethoprim
Trimethoprim selectively inhibits bacterial dihydrofolate reductase, reducing production of tetrahydrofolate and consequently interfering with bacterial nucleic-acid and protein synthesis.
The two components therefore act at different bacterial targets. This does not, by itself, establish that the combination always provides clinically superior activity or prevents resistance.
9. Spectrum of Activity
The antimicrobial spectrum is determined by the susceptibility of the infecting organism to each component and by local resistance patterns.
Erythromycin has documented activity against susceptible organisms including several Gram-positive organisms, selected Gram-negative organisms such as Bordetella pertussis, Legionella pneumophila, Neisseria species and Haemophilus influenzae, as well as Mycoplasma, Ureaplasma, Chlamydia and certain other organisms.
Trimethoprim has activity against selected Gram-positive and Gram-negative organisms, including susceptible E. coli, Proteus mirabilis, Klebsiella pneumoniae, Enterobacter species, and some staphylococci. Important intrinsic or clinically relevant resistance exists in several organisms.
Therefore, the original claim that the combination "covers most Gram-negative and Gram-positive bacteria" is too broad and should be removed.
There is also no adequate basis for describing Erythroprim as an antiamoebic medicine. Trimethoprim is not an established antiamoebic drug, and erythromycin should not be presented as an antiamoebic component.
10. Pharmacokinetics
Erythromycin
Orally administered erythromycin ethylsuccinate is readily and reliably absorbed. Erythromycin distributes into many body fluids, is concentrated in the liver, and is predominantly excreted into bile. Less than 5% of an oral dose is excreted in active form in urine.
Trimethoprim
Trimethoprim is rapidly absorbed after oral administration. Approximately 10–20% is metabolized, primarily in the liver, while the remainder is principally eliminated in the urine. Its half-life is approximately 8–10 hours in the cited labeling and may be prolonged in severe renal impairment. About 50–60% of an oral dose is excreted in urine within 24 hours, much of it as unchanged drug.
The original statement that erythromycin is mainly excreted in bile and trimethoprim mainly in urine is therefore broadly correct, but the statement "trimethoprim is excreted in urine up to 60% as unchanged drug" is less precise than current labeling and should not imply that the whole 60% is unchanged drug.
11. Indications
The historical Erythroprim material lists use in bacterial infections involving the respiratory tract, gastrointestinal tract, urinary tract, ENT system, and certain other systemic infections, as well as chlamydial, spirochetal and anaerobic infections.
However, these historical indications should not all be treated as currently confirmed approved indications for the Egyptian product without access to the current manufacturer-approved leaflet.
The most defensible modern description is:
Erythroprim is intended for susceptible bacterial infections for which the prescribing clinician considers the erythromycin–trimethoprim combination appropriate.
The original wording "Antiamoebic" should be deleted.
"Respiratory tract infections," "ENT infections," "gastroenteritis," and "urinary tract infections" may appear in historical product material, but the appropriateness of treatment depends on the causative organism and current susceptibility patterns. In particular, antibiotic treatment of infectious diarrhea should not be assumed solely from the presence of diarrhea.
12. Administration
Erythroprim is administered orally.
The historical Erythroprim leaflet states that the product should be taken approximately 30–60 minutes before meals.
However, formulation-specific erythromycin products do not all have identical food instructions; for example, erythromycin ethylsuccinate suspensions have been shown to achieve comparable serum concentrations in fasting and non-fasting states. Therefore, the current product-specific leaflet should take precedence over generalized instructions about erythromycin.
The original fixed-dose regimen should not be reproduced as an automatically applicable current regimen because the currently approved Erythroprim prescribing information could not be independently verified from a current manufacturer document.
13. Method of Preparation
For the dry suspension, the product must be reconstituted before use.
The exact volume and preparation instructions for the currently marketed Erythroprim 80 mL presentation could not be independently verified from a current manufacturer leaflet in the publicly accessible sources reviewed. Therefore, no specific quantity of water should be invented.
The safe instruction is:
- Reconstitute only according to the current package/leaflet instructions.
- Use the specified water quantity and final volume indicated by the manufacturer.
- Shake thoroughly after preparation and before each dose.
- Use an appropriate measuring device for administration.
Current Egyptian market information confirms that the 80 mL product is a dry suspension requiring preparation before administration.
14. Contraindications
The following are the major clinically relevant contraindications or situations requiring avoidance, depending on the formulation and current approved labeling:
- Known hypersensitivity to erythromycin, trimethoprim, or relevant formulation components.
- Trimethoprim is contraindicated in patients with megaloblastic anemia due to folate deficiency according to its labeling.
- Erythromycin may be contraindicated in patients with significant QT prolongation or certain serious arrhythmia risks and with particular interacting medicines, depending on the product label.
The original statement that Erythroprim is absolutely contraindicated in G6PD deficiency is not supported as a general modern pharmacological statement for trimethoprim. An Egyptian Health Council guideline classifies trimethoprim as low risk in G6PD deficiency, whereas it classifies several other antibacterials as high risk.
Likewise, pregnancy should not simply be described as an absolute contraindication to the combination without qualification. Trimethoprim interferes with folate metabolism and requires particular caution in pregnancy, especially early pregnancy, whereas erythromycin itself can be used during pregnancy in appropriate circumstances.
15. Warnings & Precautions
Important precautions include:
- Use only for a suspected or confirmed susceptible bacterial infection.
- Consider local antimicrobial resistance patterns when selecting therapy.
- Use caution in renal impairment, particularly because trimethoprim is substantially renally eliminated and its half-life may increase in severe renal dysfunction.
- Use caution in hepatic disease, especially because erythromycin undergoes significant hepatic handling and has been associated with hepatic adverse effects.
- Watch for clinically significant hypersensitivity reactions.
- Monitor for hematological toxicity where prolonged or high-dose trimethoprim exposure occurs, particularly in patients at risk of folate deficiency.
- Erythromycin can prolong QT and has been associated with serious ventricular arrhythmias in susceptible patients.
- Antibiotic-associated diarrhea, including Clostridioides difficile-associated diarrhea, is possible with systemic antibacterial treatment.
- Avoid unnecessary use of antibiotics because it promotes antimicrobial resistance.
16. Drug Interactions
Erythromycin
Erythromycin is a clinically important inhibitor of CYP-mediated drug metabolism and may increase concentrations/effects of several medicines. Important examples include:
- Carbamazepine
- Digoxin
- Theophylline
- Warfarin and other oral anticoagulants
- Certain corticosteroids
- Certain benzodiazepines such as midazolam and triazolam
- Some anticonvulsants and immunosuppressants
- Certain drugs associated with QT prolongation
- Ergotamine/dihydroergotamine
- Certain statins, particularly CYP3A4-metabolized statins
- Colchicine, for which serious toxicity has been reported.
Erythromycin also has pharmacodynamic antagonism reported in vitro with certain bacteriostatic/antibacterial agents, including clindamycin, lincomycin and chloramphenicol.
The original wording "potentiate the effect of carbamazepine, corticosteroids and digoxin" is directionally correct but incomplete; the clinically relevant issue is increased exposure or effect through metabolic inhibition and/or other mechanisms.
Trimethoprim
Trimethoprim can increase the effects or concentrations of certain medicines, including:
- Warfarin and other anticoagulants — increased anticoagulant effect may occur.
- Phenytoin — trimethoprim can reduce phenytoin clearance and increase its half-life.
- Other folate antagonists, with greater risk of folate-related toxicity.
- Medicines affecting renal function or potassium balance may also require attention when trimethoprim is used.
Therefore, the original interaction section is valid in principle but substantially incomplete.
17. Side Effects
Erythromycin
Common or recognized adverse effects include:
- Nausea
- Vomiting
- Abdominal discomfort/cramping
- Diarrhea and other gastrointestinal disturbances
- Skin rash or other hypersensitivity reactions
Less frequent but clinically important reactions include:
- Hepatic injury/cholestatic hepatitis
- QT prolongation and serious ventricular arrhythmias in susceptible patients
- Reversible hearing impairment, particularly with high doses or predisposed patients
- Rare severe cutaneous reactions.
Therefore, the original description of erythromycin adverse effects as simply "infrequent and mild" is too reassuring and should be removed.
Trimethoprim
Possible adverse effects include:
- Nausea and vomiting
- Rash and hypersensitivity reactions
- Folate-related hematological abnormalities
- Megaloblastic anemia
- Leukopenia, thrombocytopenia, or other marrow suppression, especially with high-dose or prolonged treatment
- Hyperkalemia and hyponatremia in susceptible patients
- Increases in serum creatinine caused partly by inhibition of tubular creatinine secretion, without necessarily representing a true fall in GFR
- Rare serious hypersensitivity reactions.
The original statement that trimethoprim adverse effects are simply "dose and course related" is incomplete but captures an important part of the risk pattern.
18. Use in Special Populations
Pregnancy
Trimethoprim is a folate antagonist and requires particular caution during pregnancy, especially during the first trimester. Its use should be based on a clinician's benefit–risk assessment and, where appropriate, folate considerations. Erythromycin itself is commonly used in pregnancy when clinically indicated.
Therefore, the blanket statement "Erythroprim should not be used in pregnancy" is too absolute as a general scientific statement.
Breastfeeding
Both erythromycin and trimethoprim can enter breast milk. Trimethoprim labeling advises caution in breastfeeding because of its effect on folate metabolism.
Infants and children
Pediatric use should be based on the child's age, weight, infection, renal function, and the specific current product information. The general pediatric dosing statements in the historical Erythroprim leaflet should not be treated as a universally validated modern dosing schedule.
In particular, current trimethoprim labeling notes that safety/effectiveness for trimethoprim monotherapy has not been established in very young infants and that dosing requires attention to renal function and age.
Elderly patients
Older adults may have greater susceptibility to renal impairment, drug interactions, electrolyte disturbances, and adverse effects. Renal function and concomitant medicines should therefore be considered.
Renal impairment
Dose selection may require modification because trimethoprim is substantially renally eliminated and its half-life increases with severe renal impairment.
Hepatic impairment
Use caution because erythromycin undergoes substantial hepatic handling and has recognized hepatic adverse effects.
19. Storage Conditions
A current manufacturer-specific storage statement for the Erythroprim 80 mL presentation could not be independently verified from the publicly accessible sources reviewed.
Therefore, the safest wording is:
Store according to the temperature, light, and post-reconstitution instructions stated on the current Erythroprim package and leaflet. Keep out of the reach and sight of children. Do not use the reconstituted suspension beyond the manufacturer-specified in-use period.
A specific temperature or post-reconstitution shelf-life should not be inserted without the current product leaflet.
20. Additional Sections
Current Egyptian Market Presentations
Current Egyptian market listings reviewed in August 2026 identify:
| Commercial presentation | Active combination | Manufacturer |
|---|---|---|
| Erythroprim 20 f.c. tab | Erythromycin + Trimethoprim | Misr |
| Erythroprim dry susp. 80ml | Erythromycin + Trimethoprim | Misr |
These presentations are currently listed in Egyptian drug-price databases, with the tablet presentation listed at approximately EGP 10.60 and the 80 mL dry suspension at approximately EGP 8.00 in the cited 2026 records. Prices are included only as market information and may change.
Historical Product Information
An older Erythroprim product commentary lists additional packaging, including 20 film-coated tablets and granules for oral suspension. It also records historical dosing instructions and the older warning against pregnancy and G6PD deficiency. These historical statements have been retained here only where useful for comparison and have not been accepted uncritically as current scientific recommendations.
Antibiotic Stewardship
The modern principle is that antibacterial medicines should be used only when there is a reasonable likelihood of bacterial infection, and therapy should be narrowed or changed when culture and susceptibility data are available.
21. Frequently Asked Questions (FAQ)
Is Erythroprim an antiamoebic medicine?
No. Erythroprim should be classified as an antibacterial combination. Calling it "antiamoebic" is not scientifically appropriate.
What does Erythroprim contain?
The historical product information specifies erythromycin plus trimethoprim. The tablet contains erythromycin base equivalent to 250 mg plus trimethoprim 80 mg, while the dry suspension contains erythromycin base equivalent to 200 mg plus trimethoprim 40 mg per 5 mL.
Does Erythroprim cover all Gram-positive and Gram-negative bacteria?
No. Its activity is limited to susceptible organisms, and resistance is clinically important. Neither erythromycin nor trimethoprim should be considered universally active against Gram-positive or Gram-negative bacteria.
Is Erythroprim contraindicated in G6PD deficiency?
The historical leaflet says yes, but this is not supported as a blanket modern statement for trimethoprim. Contemporary Egyptian guidance classifies trimethoprim as low risk in G6PD deficiency. Product-specific labeling should nevertheless be checked, particularly for the complete combination.
Can Erythroprim be used during pregnancy?
It should not be treated as a blanket "safe" or blanket "absolutely contraindicated" combination. Trimethoprim is a folate antagonist and warrants particular caution, especially in early pregnancy; erythromycin itself is commonly used in pregnancy when indicated. The current product-specific prescribing information and clinician assessment should determine use.
Should the dry suspension be prepared using a guessed amount of water?
No. The exact reconstitution volume should be taken from the current package/leaflet for the specific Erythroprim presentation. It should not be inferred from the final bottle volume alone.
22. References
- Misr Company / historical Erythroprim product information — composition, historical indications, interactions, warnings, dosing and packaging.
- DailyMed — Trimethoprim Tablets — pharmacokinetics, mechanism, resistance, indications, contraindications, warnings, pregnancy, breastfeeding and interactions; label updated January 26, 2024.
- DailyMed — Erythromycin Ethylsuccinate — absorption, distribution, biliary excretion and mechanism of action.
- electronic Medicines Compendium (emc) — Erythromycin SmPCs — antimicrobial spectrum, adverse effects, contraindications and clinically important drug interactions.
- Egyptian Health Council — Guidelines for G6PD-related acute hemolytic anemia — drug-risk classification including trimethoprim.
- Current Egyptian market listings for Erythroprim 20 f.c. tab and Erythroprim dry susp. 80ml — current commercial presentations, manufacturer and 2026 market data.
- Egyptian Drug Authority (EDA) — official information concerning pharmaceutical-product availability services and regulatory functions.
Final verification note: The original commentary should not be published unchanged. The most important corrections are: remove "Antiamoebic"; remove the unqualified claim that the combination covers "most" Gram-positive and Gram-negative bacteria; do not state that resistance emergence is necessarily delayed by this combination; replace the blanket G6PD contraindication with an evidence-based qualification; replace the blanket pregnancy contraindication with a trimethoprim/folate-specific risk statement; broaden the interaction and adverse-effect sections; and do not present the historical Erythroprim dosing schedule, preparation volume, or storage conditions as current unless they are confirmed against the latest manufacturer-approved leaflet.