Oblong Pharmalgin 500 mg Tablets
1. Disclaimer
This information is intended for healthcare professionals and educational reference only. It is not a substitute for the current approved product information, clinical judgment, individualized medical assessment, or advice from a qualified healthcare professional. Metamizole has important and potentially serious adverse effects, and its authorized indications, contraindications, dosing recommendations, and regulatory status may vary between countries and products.
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.
2. Summary
Oblong Pharmalgin is an oral analgesic and antipyretic tablet containing metamizole sodium (dipyrone; Analgin) 500 mg. Metamizole is a non-opioid pyrazolone analgesic with analgesic, antipyretic, and spasmolytic properties. It is used in some countries for moderate to severe acute pain and for high fever when other appropriate measures are inadequate or unsuitable.
Its clinical use requires particular attention to the rare but potentially fatal risk of agranulocytosis, as well as severe hypersensitivity reactions, hypotension, serious skin reactions, renal adverse effects, and drug-induced liver injury. Agranulocytosis is idiosyncratic, is not dose-dependent, and may occur at any time during treatment or shortly after treatment is stopped.
3. Brand Name
Oblong Pharmalgin 500 mg
The product is also listed as OBLONG PHARMALGIN film-coated tablet 500 mg in international drug-reference databases.
4. Category
- Non-opioid analgesic
- Antipyretic
- Pyrazolone derivative
- Spasmolytic analgesic
- ATC classification: N02BB02 – Metamizole sodium
Metamizole is not an antimicrobial drug and therefore has no antibacterial or other anti-infective spectrum.
5. Active Ingredient
Each tablet contains:
Metamizole sodium (dipyrone; Analgin) 500 mg
Metamizole is rapidly converted after oral administration to pharmacologically active metabolites, principally 4-methylaminoantipyrine (4-MAA) and subsequently 4-aminoantipyrine (4-AA).
6. Pharmaceutical Form & Strength
Pharmaceutical form: Film-coated tablet
Strength: 500 mg metamizole sodium per tablet
Route: Oral
Available product records identify Oblong Pharmalgin as a 500 mg film-coated tablet supplied by Arab Drug Company (ADCO).
7. Manufacturer & Marketing Authorization Holder
Manufacturer: Arab Drug Company (ADCO), Cairo, Egypt.
Available product databases identify Arab Drug Company as the laboratory/manufacturer for Oblong Pharmalgin. A separate, current regulatory designation of a different Marketing Authorization Holder could not be independently confirmed from the accessible authoritative product records; therefore no separate MAH is assigned here without reliable supporting documentation.
8. Mechanism of Action
The mechanism of action of metamizole is not completely understood.
Its analgesic and antipyretic effects appear to involve both central and peripheral mechanisms. After administration, its active metabolites, particularly 4-MAA and 4-AA, contribute substantially to its pharmacological effects. Inhibition of prostaglandin synthesis appears to contribute to its analgesic and antipyretic activity, although metamizole's pharmacology is more complex than simple classification as a conventional NSAID.
Metamizole also has clinically relevant spasmolytic activity. Its anti-inflammatory effect is comparatively less prominent than its analgesic and antipyretic effects.
9. Spectrum of Activity
Not applicable.
Pharmalgin is an analgesic and antipyretic, not an antimicrobial medicine. It therefore has no antibacterial, antiviral, antifungal, or antiparasitic spectrum.
10. Pharmacokinetics
After oral administration, metamizole is rapidly hydrolyzed to its major active metabolite, 4-methylaminoantipyrine (4-MAA), which is readily absorbed. Oral metamizole is absorbed almost completely, and food does not have a clinically relevant effect on its pharmacokinetics.
4-MAA is subsequently metabolized in the liver to additional metabolites, principally 4-aminoantipyrine (4-AA), 4-formylaminoantipyrine (4-FAA), and 4-acetylaminoantipyrine (4-AcAA). The pharmacological effects are mainly attributed to 4-MAA and 4-AA.
Approximately 90% or more of the administered radiolabeled dose is recovered in the urine within 7 days. The elimination half-life of 4-MAA after a single oral dose is approximately 2.7 hours, while the half-lives of other major metabolites are approximately 3.7–11.2 hours. Elimination of metabolites may be delayed in older adults and in patients with impaired renal or hepatic function.
11. Indications
Depending on the applicable national authorization, metamizole may be used for:
- Moderate to severe acute pain, including post-operative or post-traumatic pain.
- Colicky or spasmodic pain.
- Certain severe pain states, including pain of tumoral origin where authorized.
- High fever that does not adequately respond to other appropriate measures or first-line antipyretics.
The precise authorized indications for Pharmalgin should be confirmed against the current Egyptian approved product information.
12. Administration
Route: Oral.
For a 500 mg tablet, contemporary metamizole dosing references for adults and adolescents aged 15 years or older and weighing more than 53 kg generally use 500–1,000 mg per single dose, with doses repeated according to clinical need and generally separated by approximately 4–6 hours. A commonly used maximum is 4,000 mg per day.
Treatment should use the lowest effective dose for the shortest appropriate duration. In older, debilitated, or renally/hepatically impaired patients, repeated high doses should be avoided and dose selection should be conservative.
For this specific 500 mg product, the current locally approved Pharmalgin dosing instructions should take precedence over generalized metamizole dosing information.
13. Method of Preparation
No reconstitution or special preparation is required.
The tablet should be swallowed orally with an adequate amount of liquid. It should not be crushed or chewed unless the current product instructions specifically permit alteration of the dosage form.
14. Contraindications
Metamizole should not be used in patients with:
- Previous metamizole-induced agranulocytosis.
- Previous agranulocytosis associated with other pyrazolones or pyrazolidines.
- Existing bone-marrow dysfunction or disorders of the hematopoietic system.
- Previous serious hypersensitivity or hematological reactions to metamizole, other pyrazolones, or pyrazolidines.
- Analgesic-asthma syndrome or known analgesic intolerance with urticaria/angioedema or other serious anaphylactoid reactions to non-opioid analgesics.
- Acute intermittent hepatic porphyria.
- Genetic glucose-6-phosphate dehydrogenase (G6PD) deficiency because of the risk of hemolysis.
- Previous serious cutaneous reaction associated with metamizole.
- Third trimester of pregnancy.
15. Warnings & Precautions
Agranulocytosis and serious blood disorders
Metamizole can cause agranulocytosis, which may be life-threatening or fatal. The reaction is idiosyncratic, not dose-dependent, and may occur at any time during treatment or shortly after discontinuation, including in patients who previously tolerated metamizole without problems.
Patients should stop treatment and obtain urgent medical evaluation if they develop symptoms such as:
- Fever
- Chills
- Sore throat
- Painful sores or inflammation of the mouth, nose, throat, genital, or anal mucosa
- Unexpected infection or deterioration in general condition
A complete blood count with differential should be obtained promptly when agranulocytosis or another serious blood dyscrasia is suspected. Treatment should not be continued while awaiting confirmation when the clinical picture is suggestive. Routine blood-count monitoring solely because the patient is receiving prolonged metamizole therapy is not a substitute for prompt evaluation of suspicious symptoms.
Severe hypersensitivity
Metamizole can cause anaphylactic or anaphylactoid reactions, including bronchospasm, angioedema, severe hypotension, and anaphylactic shock. Increased caution is warranted in patients with analgesic-asthma syndrome, chronic urticaria, asthma, or previous intolerance to analgesics.
Hypotension
Hypotensive reactions may occur and can occasionally be severe. Particular caution is required in patients with pre-existing hypotension, dehydration, hypovolemia, circulatory instability, severe coronary disease, or high fever.
Serious skin reactions
Rare or frequency-unknown serious cutaneous adverse reactions, including Stevens–Johnson syndrome, toxic epidermal necrolysis, and DRESS, have been reported. Metamizole should be discontinued immediately when signs suggestive of a serious skin reaction appear and should not be restarted after such a reaction.
Liver injury
Drug-induced liver injury, including acute predominantly hepatocellular hepatitis, has been reported and may occur from several days to several months after treatment is started.
Renal impairment
Acute kidney injury, proteinuria, oliguria, anuria, renal insufficiency, and interstitial nephritis have been reported. Repeated high doses should be avoided in patients with impaired renal function.
Alcohol
Alcohol may potentiate the effects of both alcohol and metamizole. Caution or avoidance is therefore appropriate, particularly when higher doses are used.
16. Drug Interactions
Clinically important or potentially important interactions include:
- Methotrexate and other antineoplastic agents: may increase hematological toxicity; concomitant use should generally be avoided, particularly in older patients.
- Low-dose aspirin: metamizole may reduce its antiplatelet effect; caution is appropriate when aspirin is being used for cardiovascular protection.
- Chlorpromazine: concomitant use may cause severe hypothermia.
- Alcohol: pharmacodynamic effects may be potentiated.
- CYP-related interactions: metamizole may induce enzymes including CYP2B6 and CYP3A4 and may reduce exposure to some medicines, including bupropion, efavirenz, methadone, valproate, cyclosporine, tacrolimus, and sertraline.
- Other possible interactions have been reported with anticoagulants, captopril, lithium, triamterene, antihypertensives, and diuretics, although the extent to which these are specifically attributable to metamizole is less certain.
17. Side Effects
Important adverse reactions associated with metamizole include:
Hematological
- Agranulocytosis, including fatal cases
- Leukopenia
- Thrombocytopenia
- Aplastic anemia
- Pancytopenia
- Sepsis secondary to severe blood-cell abnormalities
Hypersensitivity and immune-mediated
- Rash
- Urticaria
- Angioedema
- Bronchospasm
- Anaphylactic or anaphylactoid reactions
- Anaphylactic shock
- DRESS
Cardiovascular
- Hypotension
- Severe circulatory reactions
- Shock
- Rare cardiac hypersensitivity syndromes such as Kounis syndrome
Skin
- Serious cutaneous reactions including Stevens–Johnson syndrome and toxic epidermal necrolysis
Renal and urinary
- Acute renal failure
- Interstitial nephritis
- Proteinuria
- Oliguria or anuria
- Other renal impairment
Gastrointestinal
- Gastrointestinal hemorrhage has been reported, particularly in some patients receiving concomitant drugs associated with gastrointestinal bleeding or following overdose.
Hepatobiliary
- Drug-induced liver injury
- Acute hepatitis
- Jaundice
- Increased liver enzymes
A harmless reddish discoloration of urine can occur because of excretion of rubazonic acid, a metamizole metabolite, particularly after high doses. This should nevertheless be distinguished from other causes of abnormal urine coloration.
18. Use in Special Populations
Pregnancy
Metamizole crosses the placenta. Current European product information contraindicates use during the third trimester because of fetal renal effects and possible premature constriction of the ductus arteriosus.
During the first and second trimesters, routine use is generally not recommended; a single dose may be considered only when clinically necessary and when suitable alternatives are unavailable, following professional assessment.
Breastfeeding
Metamizole metabolites are excreted into breast milk. Repeated use during breastfeeding should be avoided. Some current product information recommends discarding breast milk for 48 hours following a single dose.
Pediatric patients
Dosing in children should be based on age and body weight and on a formulation with an appropriate strength. A fixed 500 mg tablet is not automatically suitable for young children. Pediatric use should therefore follow the applicable approved product information and weight-based recommendations.
Older adults
Older patients may have slower elimination of metamizole metabolites and may require more conservative dosing, particularly when repeated doses are being used.
Renal or hepatic impairment
In renal or hepatic impairment, elimination of some metabolites may be delayed. Repeated high doses should therefore be avoided, and treatment should be individualized according to severity and clinical need.
G6PD deficiency
Metamizole is contraindicated in patients with genetic G6PD deficiency because of the potential risk of hemolysis.
19. Storage Conditions
Product-specific current storage conditions for Oblong Pharmalgin could not be independently verified from a current authoritative ADCO product document accessible in the reviewed sources.
The product should therefore be stored strictly according to the current package labeling or approved Egyptian product leaflet, including any specified temperature, light, moisture, and child-safety requirements.
20. Additional Sections
Overdose
Overdose may produce nausea, vomiting, abdominal pain, impaired renal function, hypotension, tachycardia, dizziness, drowsiness, central nervous system depression, convulsions, and severe cardiovascular or renal complications. Reddish urine may occur following high doses because of rubazonic acid excretion.
There is no specific antidote. Management is supportive and may require intensive medical care. Activated charcoal may be considered after recent ingestion when clinically appropriate, and extracorporeal techniques such as hemodialysis or hemofiltration may remove the principal metabolite 4-MAA.
Driving and Operating Machinery
At recommended doses, significant impairment is not generally expected; however, dizziness, hypotension, or impairment may occur, particularly at higher doses. Patients should exercise caution when driving or operating machinery, especially if alcohol has also been consumed.
Regulatory Context
Metamizole remains authorized and widely used in several countries but is not authorized in some jurisdictions because of concerns regarding agranulocytosis. Regulatory recommendations continue to emphasize early recognition of this serious adverse reaction and appropriate risk minimization. The European Medicines Agency strengthened its recommendations in 2024 following a safety review.
Clinical Monitoring
There is no single routine laboratory test that can reliably predict idiosyncratic metamizole-induced agranulocytosis. Clinical vigilance for infection-related symptoms and immediate investigation of suspicious symptoms are essential. Monitoring of renal, hepatic, or hematological parameters should be individualized according to the patient's clinical condition and duration of therapy.
21. Frequently Asked Questions (FAQ)
What is the active ingredient in Pharmalgin 500 mg?
It contains metamizole sodium 500 mg, also known as dipyrone or Analgin.
Is Pharmalgin an antibiotic?
No. It is an analgesic and antipyretic with spasmolytic properties and has no antimicrobial spectrum.
What is the most important serious adverse effect of metamizole?
Agranulocytosis is one of the most important serious risks. It can occur unpredictably, is not dose-dependent, and may become life-threatening. Fever, chills, sore throat, or painful mucosal lesions during or shortly after treatment require immediate medical evaluation.
Can metamizole be used during pregnancy or breastfeeding?
Use during pregnancy requires careful medical assessment. The third trimester is contraindicated in current European product information. Repeated use during breastfeeding should be avoided, and some current product information recommends discarding breast milk for 48 hours after a single dose.
Does red urine always indicate kidney bleeding?
No. Metamizole can cause harmless reddish urine through excretion of rubazonic acid, particularly after higher doses. Nevertheless, unexplained or persistent urinary changes should not automatically be attributed to the medicine without clinical assessment.
22. References
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European Medicines Agency (EMA). Metamizole-containing medicinal products – Article 107i referral: EMA recommends measures to minimise serious outcomes of known side effect with painkiller metamizole. 20 September 2024.
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European Medicines Agency (EMA). Metamizole – Article 31 referral: CHMP assessment report.
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European Medicines Agency (EMA). EMA recommends aligning doses of metamizole medicines and their use during pregnancy and breastfeeding. 14 December 2018.
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AEMPS/CIMA. Metamizol Pensa Pharma 575 mg – Ficha Técnica. Current product information covering indications, pharmacology, contraindications, warnings, interactions, pregnancy, lactation, adverse reactions, overdose, and pharmacokinetics.
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World Health Organization (WHO). WHO guidelines for clinical management / metamizole dosing information. 2025.
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Médecins Sans Frontières (MSF). Metamizole = Dipyrone = Noramidopyrine, oral. Current medical guidelines.
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Vademecum International. Oblong Pharmalgin film-coated tablet 500 mg, Egypt – Arab Drug Company (ADCO). Product identification, dosage form, manufacturer, ATC classification, and pharmacological information.
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Vezeeta Pharmacy. Oblong Pharmalgin 500 mg – 10 tablets. Product identification, active ingredient, manufacturer, and current Egyptian product listing.