Pleuromutilins:
- It is antibacterial drugs which act by inhibiting protein synthesis by binding to peptidyl transferase component of 50S sub-unit of ribosomes.
- This class of drugs includes tiamulin, valnemulin, retapamulin.
Tiamulin:
- It is semi-synthetic derivative of pleuromutilin obtained from Pleurotus mutilis.
- It is approved for use in animals and available as hydrogen fumarate salt for oral use.
Mechanism of action:
Tiamulin binds to 50S bacterial ribosomal sub-unit
Binds to peptidyl transferase
Break in peptide chain immediately after initiation
Inhibition of protein synthesis
Antimicrobial spectrum:
- It has broad-spectrum of activity which includes gram +ve organism, mycoplasma and anaerobes including Treponema hyodysenteriae.
- Some strains of gram -ve organisms such as Haemophilus, Bordetella, coli, Pasteurella and Actinobacillus are also susceptible to tiamulin.
Bacterial resistance:
- Bacterial resistance to tiamulin develops slowly
- Resistance is probably due to modification of ribosomal target.
Pharmacokinetics:
- It is well absorbed (>90%) when given orally
- Peak plasma concentration occurs between 2-4 hours after single oral dose.
- It is well distributed in body with high concentration found in lungs.
- These drugs are metabolized to over 20 metabolites and excreted mainly in bile, remainder excreted in urine.
Side effects/Adverse effects:
- Rarely produce redness of skin and erythema
- Oral overdosage in pigs may cause transient GI signs and CNS depression
- It may cause growth retardation when administered with ionophore antibiotics such as monensin and salinomycin.
- Inhalation may cause nose, throat & respiratory tract irritation, coughing and allergic reactions.
Contraindications and precautions:
- In animals feeding with ionophore antibiotics
Clinical use:
- It is mainly used in pigs for treatment of enzootic pneumonia.
- In mycoplasmal arthritis.
- As growth promoter in swine.
Dose:
For enzootic pneumonia
Pigs: 30-40 g/tonne feed, for 2 months
For swine dysentery
Pigs: 1.5-2 mg/kg, PO