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Azithromycin 500 mg powder for concentrate for solution for infusion – Summary of Product Characteristics (SmPC) for healthcare professionals

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Medicine status: Prescription only (POM) Details

The Summary of Product Characteristics (SmPC) is written for healthcare professionals. Patients will find plain advice in the patient information leaflet: how to take, side effects, other medicines, pregnancy and breast-feeding.

Medicine strength:
500 mg
Contains active substance:

Summary of Product Characteristics (SmPC) - Azithromycin 500 mg powder for concentrate for solution for infusion

1 NAME OF THE MEDICINAL PRODUCT

Azithromycin 500 mg powder for concentrate for solution for infusion

2 QUALITATIVE AND QUANTITATIVE COMPOSITION

Each vial contains 500 mg azithromycin (as dihydrate), equivalent to 100 mg/ml after reconstitution of the concentrate for a solution for infusion. The concentrate should be further diluted to 1mg/ml or 2mg/ml.

Excipient(s) with known effect

Sodium hydroxide – 120 mg of sodium per vial (25 mg/ml of sodium after reconstitution.

For the full list of excipients, see section 6.1.

3 PHARMACEUTICAL FORM

Powder for concentrate for solution for infusion

White to off-white powder

4 CLINICAL PARTICULARS

4.1 Therapeutic indications

Azithromycin is indicated for the treatment of the following infections in adults (see sections 4.4 and 5.1):

  • Community-acquired pneumonia (CAP)
  • Pelvic inflammatory disease (PID), always in combination with other appropriate antibacterial agent(s) (e.g. metronidazole).

Consideration should be given to official guidance on the appropriate use of antibacterial agents.

4.2 Posology and method of administration

Posology

Azithromycin should be administered as a single daily dose. Dosing recommendations for adult patients are shown in Table 1.

Table 1: Dosing recommendations for intravenous azithromycin

IndicationAzithromycin dosing regimen
Community-acquired pneumonia

500 mg once daily for at least 2 days, followed by oral dose of

500 mg daily to complete a 7- to 10-day total course of treatment.

Pelvic inflammatory disease, in combination with other appropriate antibacterial agent(s) (e.g metronidazole)

500 mg once daily for 1 to 2 days, followed by oral dose of

250 mg once daily to complete a 7-day course of treatment.

Consideration should be given to the treatment regimens, doses and duration of treatment as recommended in updated treatment guidelines for each indication.

The timing of the switch to oral therapy should be determined at the discretion of the physician and in accordance with clinical response.

Special populations

Renal impairment

No dose adjustment is required in patients with GFR ≥10 ml/min. In patients with GFR <10 ml/min azithromycin should be administered with caution (see section 5.2).

Hepatic impairment

No dose adjustment is required in patients with mild (Child-Pugh Class A) or moderate hepatic impairment (Child-Pugh Class B) (see section 5.2). No data are available in patients with severe hepatic impairment (Child-Pugh Class C). Therefore, azithromycin should be administered with caution in these patients (see section 4.4).

Elderly

No dose adjustment is required in elderly patients (see section 5.2). Since the elderly are more likely to experience proarrhythmic conditions, particular caution is recommended due to the risk of developing cardiac arrhythmia and torsade de pointes (see section 4.4).

Paediatric population

The safety and efficacy of Azithromycin for the intravenous treatment of community acquired pneumonia in the paediatric population have not been established.

There is no relevant use of Azithromycin for the treatment of pelvic inflammatory disease in children under 12 years of age while the safety and efficacy in adolescent girls have not been established.

Method of administration

For intravenous use after reconstitution and dilution.

The recommended route of administration is by intravenous infusion only. Do not administer as an intravenous bolus or an intramuscular injection. The solution concentration and rate of infusion should be either 1 mg/ml over 3 hours or 2 mg/ml over 1 hour. A dose of 500 mg azithromycin should be infused for a minimum duration of 1 hour.

For instructions on reconstitution and dilution of this medicinal product before administration, see section 6.6.

4.3 Contraindications

Hypersensitivity to the active substance, erythromycin, any macrolide or ketolide antibiotic, or to any of the excipients listed in section 6.1.

4.4 Special warnings and precautions for use

Potential for resistance

Azithromycin could favour the development of resistance due to the associated long-lasting and decreasing levels in plasma and tissues after the end of treatment (see section 5.2). Treatment with azithromycin should only be initiated after a careful assessment of the benefit and the risks, considering the local prevalence of resistance, and when preferred treatment regimens are not indicated.

Severe skin and hypersensitivity reactions

Rare serious allergic reactions, including angioedema and anaphylaxis (rarely fatal), severe cutaneous adverse reactions (SCARs) including Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug reaction with eosinophilia and systemic symptoms (DRESS), acute generalised exanthematous pustulosis (AGEP), which can be life- threatening or fatal, have been reported in association with azithromycin treatment (see section 4.8). At the time of prescription, patients should be advised of the signs and symptoms and monitored closely for skin reactions. Some of these reactions with azithromycin have resulted in recurrent symptoms and required a longer period of observation and treatment. If an allergic reaction occurs, azithromycin should be discontinued and appropriate therapy should be instituted. Physicians should be aware that reappearance of the allergic symptoms may occur when symptomatic therapy is discontinued.

QT interval prolongation

Prolonged cardiac repolarisation and QT interval, imparting a risk of developing cardiac arrhythmia and torsades de pointes, have been seen in treatment with other macrolides including azithromycin (see section 4.8). Therefore, as the following situations may lead to an increased risk for ventricular arrhythmias (including torsade de pointes) which can lead to cardiac arrest, azithromycin should be used with caution in patients with ongoing proarrhythmic conditions (especially women and elderly patients) such as patients:

  • With congenital or documented QT prolongation
  • Currently receiving treatment with other active substances known to prolong QT interval (see section 4.5)
  • With electrolyte disturbance, particularly in cases of hypokalaemia and hypomagnesaemia
  • With clinically relevant bradycardia, cardiac arrhythmia or severe cardiac insufficiency
  • Elderly patients: Elderly patients may be more susceptible to drug-associated effects on the QT interval

Hepatotoxicity

Since liver is the principal route of elimination for azithromycin, the use of azithromycin should be undertaken with caution in patients with significant hepatic disease. Cases of fulminant hepatitis potentially leading to life-threatening liver failure have been reported with azithromycin. Hepatitis, cholestatic jaundice, hepatic necrosis, and hepatic failure have also been reported with azithromycin, some of which have resulted in death (see section 4.8). Some patients may have had pre-existing hepatic disease or may have been taking other hepatotoxic medicinal products. Patients should be advised to stop azithromycin administration and to contact their physician if signs and symptoms of liver dysfunction, such as rapid developing asthenia associated with jaundice, dark urine, bleeding tendency or hepatic encephalopathy develop. In such cases liver function tests/investigations should be performed immediately.

Clostridioides difficile associated diarrhoea (CDAD), pseudomembranous colitis

CDAD and pseudomembranous colitis have been reported with azithromycin, and may range in severity from mild diarrhoea to fatal colitis (see section 4.8). CDAD and pseudomembranous colitis must be considered in patients who present with diarrhoea during or subsequent to the administration of azithromycin. Discontinuation of therapy with azithromycin and the use of supportive measures together with the administration of specific treatment for C. difficile should be considered. Medicinal products that inhibit peristalsis should not be given.

Sexually transmitted infections

Neisseria gonorrhoeae is very likely to be resistant to macrolides, including the azalide azithromycin (see section 5.1). Therefore, azithromycin is not recommended for the treatment of uncomplicated gonorrhoea and pelvic inflammatory disease unless laboratory results have confirmed susceptibility of the organism to azithromycin. If left untreated or treated sub-optimally, this condition may lead to late onset complications such as infertility and ectopic pregnancy.

Furthermore, a concomitant infection caused by Treponema pallidum should be excluded as symptoms of incubating syphilis could be masked delaying diagnosis.

For all patients with sexually transmitted urogenital infections, appropriate antibacterial therapy and microbiological follow-up tests should be initiated.

Myasthenia gravis

Exacerbations of the symptoms of myasthenia gravis and new onset of myasthenia syndrome have been reported in patients receiving azithromycin therapy (see section 4.8).

Non-susceptible organisms

The use of azithromycin may result in the overgrowth of non-susceptible organisms. If superinfection occurs, interruption of treatment or other appropriate measures may be required.

Ergot derivatives

In patients receiving ergot derivatives, ergotism has been precipitated by co-administration of some macrolide antibiotics. There are no data concerning the possibility of an interaction between ergot and azithromycin. However, because of the theoretical possibility of ergotism, azithromycin and ergot derivatives may not be co-administered.

Excipients with known effect

This medicinal product contains 120 mg sodium per vial, equivalent to 6% of the WHO recommended maximum daily intake of 2 g sodium for an adult.

Carefully consider the balance of benefits and risks before prescribing azithromycin for any patients taking hydroxychloroquine or chloroquine, because of the potential for an increased risk of cardiovascular events and cardiovascular mortality (see

section 4.5).

For the full list of excipients, see section 6.1.

4.5 Interaction with other medicinal products and other forms of interaction

Although azithromycin is a weak CYP450 inhibitor and does not interact significantly with CYP450 substrates, CYP3A4 inhibition cannot be completely ruled out. Therefore, caution is recommended in case of co-administration with CYP3A4 substrates with narrow therapeutic index.

Azithromycin is an inhibitor of the transporter P-glycoprotein (P-gp). Co-administration of azithromycin with P-gp substrates, such as digoxin and colchicine, may increase their exposure. For narrow therapeutic index drugs, caution and clinical and/or therapeutic drug monitoring and dose adjustment as appropriate are advised. The relatively long half-life of azithromycin should be taken into account in this context (see section 5.2).

Medicinal products that are known to prolong the QT interval

Azithromycin should be used with caution in patients receiving medicinal products known to prolong the QT interval (see section 4.4), such as antiarrhythmics of Classes IA (e.g.quinidine and procainamide) and III (e.g. dofetilide, amiodarone and sotalol), antipsychotic agents (e.g. pimozide), antidepressants (e.g. citalopram), fluoroquinolones (e.g. moxifloxacin and levofloxacin), cisapride, chloroquine and hydroxychloroquine.

Drug interaction information for azithromycin with potential concomitant medicinal products is summarised in the table and text below. The drug interactions described are based on clinical drug-drug interaction studies conducted with azithromycin or, where indicated, are potential drug interactions that may occur with azithromycin.

Table 2 Clinically relevant drug interactions between azithromycin and other medicinal products

Medicinal product (therapeutic area)

Interaction

Effect on exposure

MechanismRecommendation concerning co-administration
Atorvastatin (HMG CoA reductaseAzithromycin: ND Atorvastatin:Atorvastatin is a CYP3A4 and P-gpCaution should be exercised since post-

inhibitor)

Azithromycin 500 mg orally once daily for 3 days.

Atorvastatin 10 mg orally once daily

↔

AUC ↔ Cmaxsubstrate.marketing cases of rhabdomyolysis in patients receiving azithromycin concomitantly with statins have been reported.

Ciclosporin

(immunosuppressant) Azithromycin 500 mg orally once daily for 3 days.

Ciclosporin 10 mg/kg orally single dose.

Azithromycin: ND Ciclosporin:

↔ AUC

↑Cmax 24 %

Ciclosporin is a CYP3A4 and P-gp substrate with narrow therapeutic index and/or

competition for biliary excretion.

Clinical monitoring and therapeutic drug monitoring as appropriate should be performed during and after treatment with azithromycin.

Ciclosporin dose should be adjusted if required.

Colchicine (gout)

Azithromycin: ND Colchicine:

↑ 57% AUC0-t

↑ 22% Cmax

Colchicine is a P-gp substrate with

narrow therapeutic index.

Clinical monitoring is needed during and after treatment with azithromycin.
Dabigatran (oral anticoagulant)

ND

Expected: ↑ Dabigatran

Dabigatran is a P-gp substrate with

narrow therapeutic index.

Caution should be exercised since post-marketing data suggest an increased risk for haemorrhages in patients receiving azithromycin concomitantly with dabigatran.
Digoxin (cardiac glycosides)

ND

Expected: ↑ Digoxin

Digoxin is a P-gp substrate with narrow therapeutic index.Clinical monitoring, and possibly digoxin level monitoring, is needed during and after treatment with azithromycin.

Warfarin (oral

anticoagulant)

Azithromycin 500 mg orally once daily for 1 day and then 250 mg orally once daily for 4 days.

Warfarin 15 mg orally single dose.

Azithromycin: ND Warfarin: ND

No change in

prothrombin time in clinical drug

interaction study but post-marketing reports of

potentiated

anticoagulation of coumarin-type oral anticoagulants upon co-administration with azithromycin.

Not known.

A higher frequency of prothrombin time monitoring should be considered during and after treatment with azithromycin.

↑ ↓

Note: statistically significant changes by more than 10% are indicated as “ ” or “ ”, no

change as “↔”, not determined as “ND”.

No clinically relevant change in the exposure of azithromycin or the co-administered medicinal products was observed in clinical studies evaluating potential drug-drug interactions of azithromycin with carbamazepine, cetirizine, efavirenz, fluconazole, methylprednisolone, midazolam, rifabutin, sildenafil, theophylline, triazolam, trimethoprim/sulfamethoxazole and zidovudine.

4.6 Fertility, pregnancy and lactation

Pregnancy

Animal reproduction studies have been performed at doses up to moderately maternally toxic dose concentrations. In these studies, no evidence of teratogenic effects was found. There are, however, no adequate and well-controlled studies in pregnant women.

There is a large amount of data from observational studies on exposure to azithromycin during pregnancy (more than 7000 azithromycin exposed pregnancies). Most of these studies do not suggest an increased risk of adverse foetal effects such as major congenital malformations or cardiovascular malformations.

Epidemiological evidence related to the risk of miscarriage following azithromycin exposure in early pregnancy is inconclusive. Animal studies do not indicate reproductive toxicity (see section 5.3).

Azithromycin should only be used during pregnancy if clinically needed.

Breast-feeding

Azithromycin is excreted in human milk to substantial extent. No serious adverse effects of azithromycin on the breast-fed infants were observed, while effects such as diarrhoea, mucosal fungal infection as well as hypersensitivity can occur in breast-fed newborns/infants even at sub-therapeutic doses. A decision must be made whether to discontinue breast-feeding or to discontinue/abstain from azithromycin therapy taking into account the benefit of breast-feeding for the child and the benefit of therapy for the woman.

Fertility

In fertility studies conducted in rat, reduced pregnancy rates were noted following administration of azithromycin. The relevance of this finding to humans is unknown.

4.7 Effects on ability to drive and use machines

Azithromycin has a moderate influence on the ability to drive and use machines. Dizziness, drowsiness and convulsions have been reported in some patients taking azithromycin and some patients experienced visual and/or auditory impairment. This should be considered when assessing a patient’s ability to drive and use machines (see section 4.8).

4.8 Undesirable effects

Summary of the safety profile

The most commonly reported adverse reactions during treatment include diarrhoea, headache, vomiting, abdominal pain, nausea and abnormal laboratory test values. Other important adverse reactions include anaphylactic reactions, torsade de pointes, arrhythmia including ventricular tachycardia, pseudomembranous colitis and hepatic failure (see section 4.4). Severe cutaneous adverse reactions (SCARs), including Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug reaction with eosinophilia and systemic symptoms (DRESS) and acute generalised exanthematous pustulosis (AGEP) have been reported in association with azithromycin treatment (see section 4.4).

Tabulated list of adverse reactions

Adverse reactions identified through clinical trial experience and post marketing surveillance are listed below, by system organ class and frequency.

Frequencies of adverse reaction occurrence are defined as very common (≥ 1/10), common (≥ 1/100 to < 1/10), uncommon (≥ 1/1 000 to < 1/100), rare (≥ 1/10 000 to < 1/1 000), very rare (< 1/10 000), not known (cannot be estimated from the available data). Within each frequency grouping, undesirable effects are presented in order of decreasing seriousness.

Table 3: Tabulated list of adverse reactions

System organ class

Very

common

CommonUncommonRareNot known
Infections and infestations

Candida

infections

Vaginal

infection

Pneumonia Fungal infection Bacterial

infection

Pharyngitis Gastroenteritis Rhinitis

Oral

candidiasis

Blood and lymphatic system

disorders

Lymphocyte count

decreased Eosinophil count

increased Basophil

count

Leukopenia Neutropenia Eosinophilia

Platelet count increased

Haematocrit decreased

Thrombocytopenia Haemolytic anaemia

increased Monocyte count

increased Neutrophil count

increased

Immune system disordersAngioedema Hypersensitivity (see section 4.4)Anaphylactic reaction

Metabolism and nutrition

disorders

Decreased appetite
Psychiatric disordersNervousness InsomniaAgitation

Anxiety

Delirium

Hallucinations Aggression

Nervous system disordersHeadacheDizziness Dysgeusia Paraesthesia Somnolence

Syncope

Seizure

Anosmia

Ageusia

Hypoaesthesia Psychomotor hyperactivity Parosmia

Myasthenia gravis (see section 4.4)

Eye disorders

Visual

impairment

Ear and labyrinth disordersEar disorder Vertigo

Deafness

Hypoacusis Tinnitus

Cardiac disordersPalpitations

Torsade de pointes (see section 4.4) Arrhythmia including ventricular tachycardia (see section 4.4)

Electrocardiogram QT prolonged

(see section 4.4)

Vascular disordersHot flushHypotension
Respiratory, thoracic and mediastinal disordersDyspnoea Respiratory disorder Epistaxis
Gastrointestinal disordersDiarrhoea Abdominal discomfort

Vomiting Abdominal pain

Nausea

Constipation Flatulence

Dyspepsia

Gastritis

Dysphagia

Abdominal distension

Dry mouth Mouth ulceration Salivary

hypersecretion Eructation

Pancreatitis

Tongue discoloration

Pseudomembranous colitis (see section 4.4)

Hepatobiliary disorders

Hepatitis

Aspartate

aminotransferase increased

Alanine

aminotransferase increased

Blood bilirubin increased

Blood alkaline phosphatase

increased

Hepatic function abnormal

Jaundice

cholestatic

Hepatic failure (see section 4.4)

Hepatitis fulminant Hepatic necrosis

Skin and

subcutaneous tissue disorders

Rash

Pruritus Urticaria Dermatitis Dry skin

Hyperhidrosis

Acute

generalised exanthematous pustulosis

(AGEP)

Photosensitivity reaction

Drug reaction with

eosinophilia and systemic

symptoms

(DRESS)

Stevens-Johnson syndrome (SJS) Toxic epidermal necrolysis

Erythema multiforme

Musculoskeletal and connective tissue disorders

Osteoarthritis Myalgia

Back pain Neck pain

Arthralgia
Renal and urinary disorders

Dysuria

Renal pain

Blood urea

increased

Blood creatinine increased

Acute kidney failure

Tubulointerstitial nephritis

Reproductive system and

breast disorders

Intermenstrual bleeding

Testicular

disorder

General

disorders and administration site conditions

Injection site pain

Injection site inflammation

Oedema

Asthenia Malaise Fatigue

Face oedema Chest pain

Pyrexia

Pain

Peripheral

oedema

Investigations

Blood

bicarbonate decreased

Blood potassium abnormal

Blood chloride increased

Blood glucose increased Blood

bicarbonate increased

Blood sodium abnormal

Injury,

poisoning and procedural

complications

Post procedural complication

Reporting of suspected adverse reactions

Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via Yellow Card Scheme Website: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.

4.9 Overdose

Symptoms

Adverse reactions experienced with higher than recommended doses were similar to those seen at normal doses (see section 4.8). The typical symptoms of an overdose with azithromycin include gastrointestinal symptoms, i.e. vomiting, diarrhoea, abdominal pain and nausea.

Treatment

In the event of an overdose, general symptomatic treatment and support of vital functions are indicated. There are no data on the effects of dialysis on the elimination of azithromycin. However, due to the elimination mechanism of azithromycin, dialysis is unlikely to result in significant removal of the active substance.

5 PHARMACOLOGICAL PROPERTIES

5.1 Pharmacodynamic properties

Pharmacotherapeutic group: Antibacterials for systemic use, macrolides ATC code: J01FA10

Mechanism of action

The mechanism of action of azithromycin is based on the inhibition of the bacterial protein synthesis by binding to the ribosomal 50 S subunit and inhibiting translocation of the peptides.

Pharmacokinetic/pharmacodynamic relation

The efficacy depends mainly on the ratio between AUC (area under the curve) and MIC (minimum inhibitory concentration) of the causative organism.

Mechanism of resistance

Resistance against azithromycin can be based on the following mechanisms:

  • Efflux: Resistance can be caused by an increase in the number of efflux pumps in the cytoplasmic membrane. Only 14- and 15-ring-membered macrolides are concerned (so called "M" phenotype).
  • Change of target structure: Affinity to ribosomal binding sites is lowered by methylation of the 23S rRNA causing a resistance against macrolides (M), lincosamides (L) and streptogramins of the B-group (SB) (so called MLSB-phenotype). Resistance-conferring methylases are encoded by erm genes. Affinity to ribosomal binding sites is also lowered by mutations in the 23S rRNA target structure or by mutations in the large subunit ribosomal proteins.
  • Enzymatic inactivation of macrolides is only minor clinical significance.With the M-phenotype a complete cross-resistance between azithromycin, clarithromycin, erythromycin and roxithromycin is observed. The MLSB-phenotype shows an additional cross- resistance with clindamycin and streptogramin B. With the 16-ring-membered macrolide spiramycin a partial cross-resistance is exerted.

Due to low permeability of the outer membrane, most Gram-negative species are inherently resistant to macrolides.

Susceptibility testing interpretive criteria

MIC (minimum inhibitory concentration) interpretive criteria for susceptibility testing have been established by the European Committee on Antimicrobial Susceptibility Testing (EUCAST) for azithromycin and are listed here:

https://www.ema.europa.eu/documents/other/minimum-inhibitory-concentration-mic-breakpoints_en.xlsx

Prevalence of acquired resistance

The prevalence of acquired resistance may vary geographically and with time for selected species and local information on resistance is desirable, particularly when treating severe infections. As necessary, expert advice should be sought when the local prevalence of resistance is such that the utility of the agent in at least some types of infections is questionable. Particularly in the case of severe infections or therapeutic failure, a microbiological diagnosis with identification of the pathogen and determination of its susceptibility to azithromycin should be sought.

Table 4: Prevalence of acquired resistance

Commonly susceptible species

Aerobic Gram-negative microorganisms

Haemophilus influenzae

Legionella pneumophila°

Moraxella catarrhalis

Other microorganisms

Chlamydia trachomatis°

Chlamydophila pneumoniae°

Chlamydophila psittaci

Mycoplasma pneumoniae°

Species for which acquired resistance may be a problem

Aerobic Gram-positive microorganisms

Streptococcus pneumoniae+

Aerobic Gram-negative microorganisms

Neisseria gonorrhoeae

Inherently resistant organisms

Aerobic Gram-negative microorganisms

Escherichia coli

Klebsiella spp.

Pseudomonas aeruginosa

Anaerobic microorganisms

Bacteroides spp

°No updated data were available at release of tables. Primary literature, scientific standard literature and therapeutic recommendations assume susceptibility.

+Penicillin susceptible strains of Streptococcus pneumoniae are more likely to be susceptible to azithromycin than are penicillin resistant strains of Streptococcus pneumoniae.

5.2 Pharmacokinetic properties

In patients hospitalised with community-acquired pneumonia receiving single daily one-hour intravenous infusions for 2 to 5 days of 500 mg azithromycin at a concentration of 2 mg/ml, the mean Cmax ± S.D. achieved was 3.63 ± 1.60 μg/ml, the mean Ctrough (C24) after the start of the final infusion dose was 0.2 μg/ml and the mean AUC0-24 was 9.6 ± 4.8 μg.h/ml.

The mean Cmax, Ctrough (C24) and AUC0-24 values were 1.14 ± 0.14 μg/ml, 0.18 ± 0.02 μg/ml, and 8.03 ±0.86 μg·hr/ml, respectively, in normal volunteers receiving a 3-hour intravenous infusion of 500 mg azithromycin at a concentration of 1 mg/ml.

Comparison of the plasma pharmacokinetic parameters following the first and fifth daily doses of 500 mg intravenous azithromycin in healthy volunteers showed almost no change in Cmax, but there was a 40-61% increase in AUC0-24 reflecting a 2.2- to 3-fold increase in Ctrough (C24) levels.

Distribution

Azithromycin is widely and rapidly distributed from plasma to the extravascular compartment, including tissues such as tonsil, lung and gynaecological tissues as well as the intracellular compartment, in particular to polymorphonuclear leukocytes, macrophages, and monocytes. Pharmacokinetic studies have shown considerably higher azithromycin concentrations certain tissues (up to 50 times the maximum concentration observed in the plasma). This indicates an extensive binding to these tissues with a steady-state volume of distribution ranging from 23 to 31 L/kg. The redistribution phase from the intracellular to the extracellular compartment and to the plasma may result in prolonged low concentrations after treatment cessation.

Azithromycin shows low plasma protein binding, mainly to alpha 1-acid glycoprotein, and it decreases with increasing concentrations of antibiotic: 50%, 23% and 7% protein binding at concentrations of 0.05, 0.1 and 1 mg/L, respectively.

Biotransformation

Azithromycin is minimally metabolised in the liver. The primary route of biotransformation is N-demethylation of the desosamine sugar. Other pathways include O-demethylation, hydrolysis of cladinose (deconjugation of the cladinose sugar), and hydroxylation of desosamine sugar and macrolide ring.

There is no evidence of clinically relevant hepatic cytochrome CYP 3A4 induction or inhibition via the formation of a cytochrome-metabolite complex. Also, auto-induced metabolism of azithromycin by this pathway has not been detected.

Elimination

Azithromycin is mainly eliminated by (active) biliary excretion mostly as unchanged drug, but also as metabolites which are devoid of antibacterial activity. Urinary excretion represents a minor route of elimination with less than 6% of an oral dose and around 20% of the drug that reaches the systemic circulation excreted in urine. More than 50% of faecal, and 12% or urinary excretion is in the form of unchanged compound.

Following the administration of a single 500 mg azithromycin dose, a plasma clearance of 630 ml/min was estimated with a terminal half-life of approximately 68 hours. Renal clearance is generally in the range of 100-189 ml/min, substantially smaller than plasma clearance as expected due to the relatively poor contribution of the renal route to elimination.

Linearity/non-linearity

Following oral administration of an immediate release formulation, dose proportionality on AUC0-24 and Cmax was shown in the range of 250 mg to 1000 mg.

Special populations

Renal Impairment

Azithromycin pharmacokinetics was investigated in 43 adults (21 to 85 years of age) following the oral administration of a single 1.0 g dose of azithromycin (4 x 250 mg capsules) to subjects with GFR >80 ml/min (n =12), subjects with GFR between 10 and 80 ml/min (n = 12) and subjects with GFR <10 ml/min (n = 19).

The pharmacokinetics of azithromycin in subjects with GFR between 10 and 80 ml/min were not affected (mean Cmax and AUC0-120 increased by 5.1% and 4.2%, respectively compared to subjects with GFR >80 ml/min). The mean Cmax and AUC0-120 increased 61% and 35%, respectively, in subjects with GFR <10 ml compared to subjects with GFR >80 ml/min.

No data are available for subjects undergoing dialysis, but due to the elimination mechanism of azithromycin, dialysis is unlikely to result in significant removal of the active substance.

Hepatic Impairment

Azithromycin pharmacokinetics was investigated in 22 adults following the oral administration of a single 500 mg dose of azithromycin (2 x 250 mg capsules) to subjects with normal hepatic function (n = 6), Child-Pugh A (n = 10) and Child-Pugh B (n = 6). The pharmacokinetics of azithromycin in subjects with Child-Pugh A and B were 3% and 19% lower on AUC0-inf and 34% and 72% higher on Cmax, respectively, compared to subjects with normal hepatic function.

Elderly

In elderly volunteers (> 65 years) given azithromycin 500 mg (2 x 250 mg capsules) on day 1 followed by 250 mg from days 2 to 5 in the fasted state the AUC0-24 on Days 1 and 5 were 3.0 and 2.7 μg•h/ml, respectively. A 29% higher AUC 0-24, a 8% higher Cmax and a 37.5% higher Tmax than in younger volunteers (<40 years) were observed at day 5. Since these differences are not considered clinically significant, no dose adjustment is required for elderly subjects with normal renal and hepatic function.

5.3 Preclinical safety data

Non-clinical data based on conventional studies of safety pharmacology, repeated dose toxicity and genotoxicity did not indicate adverse reactions clearly relevant to humans not already considered in other sections of the SmPC.

However, phospholipidosis (intracellular phospholipid accumulation) has been observed in several tissues of mice, rats, and dogs given multiple doses of azithromycin. Phospholipidosis has been observed to a similar extent in the tissues of neonatal rats and dogs. The effect has been shown to be reversible after cessation of azithromycin treatment. The significance of this finding for humans is in general unknown.

In animal studies for embryotoxic effects performed up to moderately maternal toxic doses (2 to 3 times the maximum recommended adult daily dose of (500 mg based on body surface area), no teratogenic effect was observed in mice and rats. Azithromycin was shown to cross the placenta. In rats, azithromycin doses of 100 and 200 mg/kg bodyweight/day (2 to 3 times the maximum recommended adult daily dose of 500 mg based on body surface area) led to mild retardation of foetal ossification and in maternal weight gain. In peri- and postnatal studies in rats, mild retardation following treatment with azithromycin doses of 200 mg/kg/day (3 times the maximum recommended adult daily dose of 500 mg based on body surface area) was observed.

6 PHARMACEUTICAL PARTICULARS

6.1 List of excipients

Citric acid,

Sodium hydroxide (for pH adjustment)

6.2 Incompatibilities

This medicinal product must not be mixed with other medicinal products except those mentioned in section 6.6.

6.3 Shelf life

Unopened vial: 24 months

Stability of the reconstituted solution (prepared accordingly to the instructions given in section 6.6):

Chemical and physical in-use stability has been demonstrated for 24 hours at 30°C. From a microbiological point of view, unless the method of opening/reconstitution precludes the risk

of microbial contamination, the product should be used immediately. If not used immediately, in-use

storage times and conditions prior to use are the responsibility of the user.

Stability of reconstituted and diluted solution (prepared according to the instructions given in section

6.6):

Chemical and physical in-use stability has been demonstrated for 24 hours at 30°C and for 7 days at

2°C – 8°C.

From a microbiological point of view, the reconstituted and diluted solution should be used

immediately. If not used immediately, in-use storage times and conditions prior to use are the

responsibility of the user and would normally not be longer than 24 hours at 2°C – 8°C, unless

reconstitution and dilution has taken place in controlled and validated aseptic conditions.

6.4 Special precautions for storage

This medicine does not require any special storage conditions. For storage conditions after reconstitution, or reconstitution and dilution of the medicinal product, see section 6.3.

6.5 Nature and contents of container

10ml glass vial containing white to off-white powder with a rubber stopper and aluminium cap.

Hospital packs containing 1 vial.

6.6 Special precautions for disposal

Preparation of the infusion solution:

Reconstitution

Azithromycin 500 mg powder for solution for infusion is for single use only. The initial solution of azithromycin is prepared by adding 4.8 ml of sterile water for injections to a 500 mg vial of powder to get 5 mL of concentrate solution (using a standard 5 ml syringe so the volume of water of 4.8 ml can be measured accurately). The contents of the vial should be shaken until all of the powder is dissolved. Each ml of the solution prepared in this way contains 100 mg azithromycin (100 mg/mL). The reconstituted medicinal product is chemically and physically stable for 24 hours, when stored at

30°C.

Parenteral administration drugs should be inspected visually for particulate in suspension prior to

administration. Only clear solutions practically free from particles should be used. If particulate in suspension is evident in reconstituted solution, the drug solution should be discarded.

The reconstituted solution must be further diluted prior to administration as instructed below.

Dilution

For a concentration of 1.0 mg/ml, transfer 5 ml of the 100 mg/ml azithromycin solution to 500 ml of any of the diluents listed below.

For a concentration of 2.0 mg/ml, transfer 5 ml of the 100 mg/ml azithromycin solution to 250 ml of any of the diluents listed below.

Diluents:

0.9% Sodium Chloride Injection

0.45% Sodium Chloride

5% Dextrose in Water for Injection

Lactated Ringer’s Injection

5% Dextrose in 0.45% Sodium Chloride Injection with 20 mEq Potassium Chloride 5% Dextrose in Lactated Ringer’s Injection

5% Dextrose in 0.3% Sodium Chloride Injection

5% Dextrose in 0.45% Sodium Chloride Injection

Concentration (mg/mL) of

final infusion solution

Quantity of diluent (mL)Time of infusion
1.0 mg/mL500 mL3 hours
2.0 mg/mL250 mL1 hour

Diluted solutions, prepared according to the instructions, are chemically and physically stable for 24

hours at 30°C, or for 7 days if stored at 2°C – 8°C.

Any unused medicinal product or waste material should be disposed of in accordance with local

requirements.

7 MARKETING AUTHORISATION HOLDER

Kensington Pharma Limited,

Unit A Newlands House, 60 Chain House Lane, Whitestake, Preston, Lancashire, PR4 4LG, United Kingdom.

8 MARKETING AUTHORISATION NUMBER(S)

PL 44853/0091

9 DATE OF FIRST AUTHORISATION/RENEWAL OF THE

AUTHORISATION

15/12/2021

10 DATE OF REVISION OF THE TEXT

22/04/2026

About this document

Source: MHRA - Medicines and Healthcare products Regulatory Agency (products.mhra.gov.uk) · Marketing authorisation: PL 44853/0091

Last revision stated in the text: 22 April 2026 · MHRA data as of 13 October 2026

Found a mistake? Tell us on the contact page.

The information on this site does not replace the advice of a doctor or pharmacist.

Facts about Azithromycin 500 mg powder for concentrate for solution for infusion

Prescription needed? Yes, prescription-only medicine (POM)
Active substance Azithromycin
Strength 500 mg
Pharmaceutical form Powder for solution for infusion
White to off-white powder
How is it taken Intravenous
Excipients Citric acid,, Sodium hydroxide (for pH adjustment)
Pack sizes 1 vial
Is it available? Listed as available (NHS Dictionary of Medicines and Devices – not a record of current supplies)
Shelf life Unopened vial: 24 months
Stability of the reconstituted solution (prepared accordingly to the instructions given in section 6.6):
Chemical and physical in-use stability has been demonstrated for 24 hours at 30°C. From a microbiological point of view, unless the method of opening/reconstitution precludes the risk
of microbial contamination, the product should be used immediately. If not used immediately, in-use
storage times and conditions prior to use are the responsibility of the user.
Stability of reconstituted and diluted solution (prepared according to the instructions given in section
6.6
):
Chemical and physical in-use stability has been demonstrated for 24 hours at 30°C and for 7 days at
2°C – 8°C.
From a microbiological point of view, the reconstituted and diluted solution should be used
immediately. If not used immediately, in-use storage times and conditions prior to use are the
responsibility of the user and would normally not be longer than 24 hours at 2°C – 8°C, unless
reconstitution and dilution has taken place in controlled and validated aseptic conditions.
Storage This medicine does not require any special storage conditions. For storage conditions after reconstitution, or reconstitution and dilution of the medicinal product, see section 6.3.
Drug group (ATC) Antibacterials for systemic use, macrolides
  1. J Antiinfectives for systemic use
    1. J01 Antibacterials for systemic use
      1. J01F Macrolides, lincosamides and streptogramins
        1. J01FA Macrolides
          1. J01FA10 azithromycin
Marketing authorisation PL 44853/0091 (first authorised 15 December 2021)
Marketing authorisation holder Kensington Pharma Limited
Codes GTIN 5060467000345 · BNF 05010500

Sources: the MHRA product information (products.mhra.gov.uk) and the NHS Dictionary of Medicines and Devices (dm+d), release 10.1.0 of 12 October 2026, NHS Business Services Authority. Contains public sector information licensed under the Open Government Licence v3.0.