ZIROMIN

Indications

• Bacterial infections
• Mild to moderate typhoid due to multiple-antibacterial resistant organisms
• Respiratory-tract infections
• Otitis media
• Skin and soft tissue infections
• Chlamydia trachomatis genital infection
• Chronic Pseudomonas aeruginosa infection in cystic fibrosis
• Prevention of group A streptococcal infection in patients allergic to penicillin

Dosage

Children: Child 6 months–17 years: 10 mg/kg once daily (max. per dose 500 mg) for 3 days, repeated after 1 week if necessary. Refer to BNF for Children for specific dosing based on age and weight.

Adults: 500 mg once daily for 3 to 5 days depending on the infection being treated. For certain cases, doses may be adjusted based on clinical judgment.

Mechanism of action

Azithromycin binds to the 50S ribosomal subunit of bacteria, inhibiting protein synthesis and thus preventing bacterial growth.

Pharmacodynamics

Azithromycin exhibits bacteriostatic activity against susceptible bacteria. It has a long half-life, allowing for once-daily dosing and effective treatment of infections.

Pharmacokinetics

Azithromycin is well-absorbed after oral administration, with a bioavailability of approximately 37%. It penetrates well into tissues, with a half-life of about 68 hours, and is primarily excreted in bile, with minimal renal excretion.

Adverse effects

• Appetite decreased
• Diarrhoea
• Dizziness
• Gastrointestinal discomfort
• Headache
• Hearing impairment
• Insomnia
• Nausea
• Pancreatitis
• Paraesthesia
• Skin reactions
• Taste altered
• Vomiting
• Angioedema
• Anxiety
• Arrhythmias
• Chest pain
• Constipation
• Drowsiness
• Eosinophilia
• Hepatic disorders
• Leucopenia
• Neutropenia
• Palpitations
• QT interval prolongation
• Severe cutaneous adverse reactions (SCARs)
• Tinnitus
• Vertigo
• Antibiotic associated colitis
• Myasthenia gravis
• Nephritis tubulointerstitial
• Hallucination
• Hypotension
• Seizure
• Acute kidney injury
• Aggression
• Akathisia
• Hemolytic anemia
• Syncope

Interactions

• Azithromycin + ticagrelor: Moderate (increases exposure)
• Azithromycin + aliskiren: Unknown (increases exposure)
• Azithromycin + aminophylline: Unknown (increases exposure)
• Azithromycin + colchicine: Unknown (increases exposure)
• Azithromycin + erlotinib: Unknown (increases exposure)
• Azithromycin + lomitapide: Unknown (increases exposure)
• Azithromycin + rimegepant: Unknown (increases exposure)
• Azithromycin + taxanes: Unknown (increases exposure)
• Azithromycin + docetaxel: Unknown (increases exposure)
• Azithromycin + paclitaxel: Unknown (increases exposure)

Precautions

• Use with caution in patients with electrolyte disturbances
• Use with caution if estimated glomerular filtration rate is less than 10 mL/minute/1.73 m2
• Predisposition to QT interval prolongation may be aggravated

Indications

• Mild to moderate dehydration
• Severe dehydration
• Diarrhea-related dehydration
• Vomiting-related dehydration
• Heat-related illnesses
• Post-operative fluid replacement

Dosage

Children: In children, the oral rehydration solution is typically administered at a rate of 75

Adults: The specific dosage for rehydration will vary based on the severity of dehydration. In mild cases, oral rehydration solutions can be administered at a rate of 50-100 mL/kg over 2-4 hours. For moderate to severe dehydration, intravenous fluids may be indicated, and specific protocols should be followed based on clinical guidelines.

Mechanism of action

Dehydration itself does not have a mechanism of action as it is a physiological state rather than a pharmacological agent. However, the treatment for dehydration typically involves the administration of fluids and electrolytes, either orally or intravenously, to restore hydration status. The rehydration process helps to restore normal blood volume and electrolyte balance, facilitating cellular functions and overall metabolic processes.

Pharmacodynamics

The pharmacodynamics of rehydration solutions involve the restoration of body fluid levels and the correction of electrolyte imbalances. Oral rehydration solutions (ORS) contain a balanced ratio of salts and sugars, which enhance the absorption of water in the intestines. This process helps to re-establish osmotic balance, improve hydration, and support physiological functions. In severe cases, intravenous fluids may be required to rapidly replenish lost fluids and electrolytes.

Pharmacokinetics

The pharmacokinetics of rehydration fluids depend on the type of fluid administered. Oral rehydration solutions are absorbed primarily in the small intestine, with the absorption rate influenced by the osmolarity and composition of the solution. Intravenous fluids are distributed directly into the bloodstream, with effects seen almost immediately. The elimination of excess fluids occurs through renal excretion, which helps maintain homeostasis.

Contra-indications

• Hypersensitivity to the active substance or any of the excipients
• Severe dehydration
• Acute kidney injury

Adverse effects

• Electrolyte imbalance
• Hypotension
• Dizziness
• Dry mouth
• Thirst
• Skin rash
• Nausea
• Vomiting

Interactions

• Caution with concomitant use of diuretics
• May interact with other medications affecting electrolyte levels
• Potential interaction with medications that affect kidney function

Precautions

• Use with caution in patients with renal impairment
• Monitor electrolyte levels during therapy
• Ensure adequate hydration during treatment

Pregnancy

Use only if clearly needed and prescribed by a healthcare professional. Risk-benefit should be considered.

Breast-feeding

Consult healthcare provider before use. Monitor infant for any adverse effects.

Storage

Store at room temperature, away from moisture and heat. Keep out of reach of children.

Formulations

• Oral solution
• Oral powder
• Intravenous solution

Mechanism of action

In order to replicate, bacteria require a specific process of protein synthesis, enabled by ribosomal proteins. Azithromycin binds to the 23S rRNA of the bacterial 50S ribosomal subunit. It stops bacterial protein synthesis by inhibiting the transpeptidation/translocation step of protein synthesis and by inhibiting the assembly of the 50S ribosomal subunit,. This results in the control of various bacterial infections,. The strong affinity of macrolides, including azithromycin, for bacterial ribosomes, is consistent with their broad‐spectrum antibacterial activities. Azithromycin is highly stable at a low pH, giving it a longer serum half-life and increasing its concentrations in tissues compared to erythromycin. Azithromycin usually is bacteriostatic, although the drug may be bactericidal in high concentrations against selected organisms. Bactericidal activity has been observed in vitro against Streptococcus pyogenes, S. pneumoniae, and Haemophilus influenzae. Azithromycin inhibits protein synthesis in susceptible organisms by penetrating the cell wall and binding to 50S ribosomal subunits, thereby inhibiting translocation of aminoacyl transfer-RNA and inhibiting polypeptide synthesis. The site of action of azithromycin appears to be the same as that of the macrolides (i.e., erythromycin, clarithromycin), clindamycin, lincomycin, and chloramphenicol. The antimicrobial activity of azithromycin is reduced at low pH. Azithromycin concentrates in phagocytes, including polymorphonuclear leukocytes, monocytes, macrophages, and fibroblasts. Penetration of the drug into phagocytic cells is necessary for activity against intracellular pathogens (e.g., Staphylococcus aureus, Legionella pneumophila, Chlamydia trachomatis, Salmonella typhi).

Pharmacodynamics

Macrolides stop bacterial growth by inhibiting protein synthesis and translation, treating bacterial infections. Azithromycin has additional immunomodulatory effects and has been used in chronic respiratory inflammatory diseases for this purpose.