Penicillins (β-Lactams Antibiotics)
Drugs:
- Benzylpenicillin-Na+ / K+ (Solution: IV, IM): Quick absorption, quick excretion (Narrow but high concentration peak)
- Benzylpenicillin-Procaine = Procaine-Penicillins (Suspension: IM, SC): Depot injection, slow absorption, long duration
- Benzylpenicillin-Benzathine (Suspension: IM, SC): Very slow absorption, very long duration
- Often combined with Benzylpenicillin-Procaine for higher concentration (above MIC)
- Phenoxymethyl-Penicillin (PO): Only oral Narrow Spectrum Penicillins
- Penethamat (IM): Only Narrow Spectrum Penicillins that can cross BBB and BMB
- Combination of Narrow Spectrum Penicillins:
- Procaine-Penicillin + Benzathine-Penicillin + Dihydrostreptomycin: Synergistic effect
Antibacterial spectrum:
- Most of the Gr+ bacteria:
- Except:
- Acid-fast bacteria (Mycobacterium)
- Staphylococcus (β-Lactamase production)
- Enterococcus (their PBP have a low affinity to Narrow Spectrum Penicillins)
- Except:
- Some Gr-:
- Fastidious bacteria: Pasteurella, Haemophilus, Actinobacillus, Mannheimia
- They produce β-Lactamase in quantities too small to provide resistance
- They are associated with Respiratory infections
- Anaerobes: Bacteroides, Fusobacterium
- They are associated with Oral cavity infections and Bite wounds
- Others: Leptospira, Borrelia
- They are associated with Vector borne diseases
- Most resist due to β-Lactamase production degrading the Penicillins
- Fastidious bacteria: Pasteurella, Haemophilus, Actinobacillus, Mannheimia
Pharmacokinetics:
- Absorption:
- Weak PO absorption
- Except for Phenoxymethyl-Penicillin
- Generally injected (Parenteral)
- Weak PO absorption
- Distribution:
- Poor distribution
- Except for Penethamat that can cross the BBB and the Blood Milk Barrier and be used to treat Streptococcus caused Mastitis
- Poor distribution
- Metabolism: Minimal
- Excretion: Mainly via Kidney
Adverse effects: Almost non-toxic
- Allergy, Non immunological anaphylactic reactions (Anaphylactoid)
- Dysbacteriosis
- Herbivorous rodents (Degu, Chinchilla, Hamster, Guinea pig, Rabbits) and Horses are very sensitive to Dysbacteriosis
- It is not forbidden though, but use with care
- Herbivorous rodents (Degu, Chinchilla, Hamster, Guinea pig, Rabbits) and Horses are very sensitive to Dysbacteriosis
- Benzylpenicillin-Procaine:
- Excitement and arrythmia in foals and piglets
- Lack of Procainase in their plasma enzymes
- Forbidden for race horses 2 weeks before the race (Doping)
- Excitement and arrythmia in foals and piglets
Indication:
- Frequent:
- Necrotic enteritis mostly in Pigs and Chicken (Clostridium perfringens)
- Streptococcosis:
- Horse strangles (*S. equi ssp. equi)
- Mastitis (S. uberis, S. dysgalactiae, S. Agalactiae)
- S. suis: Meningitis, Septicaemia, Arthritis
- S. canis: Metritis, Septicaemia
- Penethamat for Meningitis (Cross BBB)
- Infrequent:
- Respiratory infections (from Fastidious Gr- bacteria)
- Swine erysipelas (Erysipelothrix rhusiopathiae)
- Anthrax (Bacillus anthracis)
- Tetanus (Clostridium tetani)