Pentaxim Mechanism of Action

Pharmacotherapeutic group: Bacterial and viral vaccines, combined. ATC code: J07CA06.
Pharmacology: Pharmacodynamics: Diphtheria and tetanus toxins are detoxified using formaldehyde and then purified.
The poliomyelitis vaccines is obtained from the propagation of poliomyelitis virus types 1, 2 and 3 on Vero cells, purified, then inactivated by formaldehyde.
The acellular pertussis components (PT and FHA) are extracted from Bordetella pertussis cultures, then purified. The pertussis toxin (PT) is detoxified by glutaraldehyde and corresponds to the pertussis toxoid (PTxd). The FHA is native. It has been shown that PTxd and FHA are two components of major importance for protection against pertussis.
The PRP capsular polysaccharide (polyribosyl ribitol phosphate: PRP) is extracted from the culture of Haemophilus influenzae type b and conjugated to the tetanus protein (T) to give the PRP-T conjugate vaccine.
The PRP capsular polysaccharide (polyribosyl ribitol phosphate: PRP) induces an anti-PRP serological response in humans. However, as for all polysaccharide antigens, the immune response is thymo-independent, characterised by a low immunogenicity in infants and by the absence of a booster effect before the age of 15 months. The covalent bond of the Haemophilus influenzae type b capsular polysaccharide to a carrier protein, the tetanus protein, enables the conjugate vaccine to behave like a thymo-dependent antigen inducing a specific anti-PRP serological response in infants and to obtain a booster effect.
Immune response after primary vaccination: Immunogenicity studies in infants have shown that, one month after the third dose of the primary vaccination, all (100%) developed a seroprotective antibody level (> 0.01 IU/mL) to both diphtheria and tetanus antigens.
As for pertussis, one month after the third dose of the primary vaccination, 93% of infants achieved a four-fold rise in PT antibodies and more than 88% in FHA antibodies.
At least 99% of children had seroprotective antibody titres to poliomyelitis virus types 1, 2 and 3 (≥ 5 as expressed by reciprocal of dilution in seroneutralisation).
At least 97.2% of infants achieved anti PRP titres above 0.15 μg/mL one month after the third dose of the primary vaccination.
Immune response after the booster: After the first booster dose (16-18 months), all the toddlers developed protective antibodies against diphtheria (> 0.1 IU/mL), tetanus (> 0.1 IU/mL), poliomyelitis viruses (≥ 5 as expressed by reciprocal of dilution in seroneutralisation).
The seroconversion rate in pertussis antibodies (titres higher than four-fold the pre-vaccinal titers) is at least 98% for PT (EIA) and 99% for FHA (EIA).
An antibody titre anti-PRP ≥1.0 μg/mL was reached in all toddlers.
A follow-up study of pertussis immunogenicity in children at 5-6 years of age has shown that the antibody titres anti-PT and anti-FHA of children vaccinated for primary course and booster with acellular combined vaccines were at least equivalent to those observed at the same age in children vaccinated with whole pertussis combined vaccines.
Pharmacokinetics: Not applicable.
Toxicology: Preclinical safety data: Non-clinical data revealed no special hazard for humans based on conventional acute toxicity, repeat dose toxicity and local tolerance studies.