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Hepatitis B Vaccine (rDNA)

Category Active immunizing agent.

      Recombinant Hepatitis B Vaccine is a noninfectious subunit viral vaccine containing hepatitis B surface antigen (HBsAg) that stimulates active immunity to hepatitis B virus infection. The antigen is obtained by recombinant DNA technology and adsorbed onto suitable adjuvant(s) such as aluminium hydroxide or hydrated aluminium phosphate.

      The vaccine complies with the requirements stated under Vaccines, with the following modifications. 

Description Whitish turbid suspension, free from evident clumps after shaking.

Strengths available For pediatric, 5 and 10 μg of hepatitis B surface antigen per 0.5 ml; for adults, 10, 20 and 40 μg of hepatitis B surface antigen per ml.

Dose Intramuscular, at deltoid region (for newborn infants injection at anterolateral thigh is more preferable).

      Adults: 10 to 20 μg, the volume injected usually not exceeding 1 ml.

      Children under 10 years of age: 5 to 10 μg, the volume injected usually not exceeding 0.5 ml.

      Dialysis patients and immunocompromized patients: as directed by the physician.

      The dose may vary depending on the specific preparation used, the recipient’s age, the HBsAg status of the mother (for neonates), and the presence of underlying disease.

Contra-indication

1. It is contra-indicated in individuals with hypersensitivity to yeast or any component of the vaccines.

2. It is not for intravenous administration.

Warning

          1. It may cause soreness, pain, induration, tenderness, pruritus, erythema, ecchymosis, swelling, warmth, burning, and nodule formation at the injection site.

          2. Fatigue, weakness, headache or fever may occur.

          3. It should be used with caution in individuals with thrombocytopenia or a bleeding disorder (e.g., hemophilia) since bleeding may occur following intramuscular administration of the drug.

          4. It should be administered with caution to individuals with severely compromized cardiopulmonary status or to other individuals in whom a febrile or adverse systemic reaction could pose a substantial risk.

          5. Unrecognized hepatitis B virus infection may be present in some individuals at the time of vaccination since the infection has a long incubation period; recombinant hepatitis B vaccine may not prevent infection in these individuals. 6. For individuals receiving immunosuppressive therapy, deferral of vaccination for not less than 3 months after therapy may be considered.

Additional information Hemodialysis patients and immunocompromized patients (i.e., those with immunodeficiencies and those receiving immunosuppressive therapy) generally require higher doses of recombinant hepatitis B vaccine than other individuals to stimulate adequate circulating antibody titers.

Expiration date When stored under the prescribed conditions, the expiration date is not later than 3 years from the date of the last satisfactory test for potency.

Labelling Complies with the “General Information for Biological Products” p. 177. In addition the label on the container states (1) the amount of HBsAg per container; (2) the type of cells used for production of the vaccine; (3) the name and amount of the adjuvant(s) used.

Identification The assay or, where applicable, the electrophoretic profile, may serve as an identification test.

Antimicrobial preservative Where applicable, determine the amount of antimicrobial preservative by a suitable chemical or physico-chemical method. The amount is not less than the minimum amount shown to be effective and is not more than 115 per cent of that stated on the label.

Pyrogens Complies with the “Pyrogen Test” (Appendix 8.2), using one human dose of the vaccine per each rabbit.

Assay

      The assay of Recombinant Hepatitis B Vaccine is carried out either in vivo, by comparing in given conditions its capacity to induce specific antibodies against hepatitis B surface antigen (HBsAg) in mice or guineapigs with the same capacity of a reference preparation, or in vitro, by an immunochemical determination of the antigen content.

      IN VIVO ASSAY

      Selection and distribution of the test animals Use in the test healthy mice from the same stock, about 5 weeks old. The strain of mice used for this test must give a significant slope for the dose-response curve to the antigen; mice with haplotype H-2^q or H-2^d are suitable. Healthy guinea-pigs weighing 300 to 350 g (about 7 weeks old) from the same stock are also suitable. Use animals of the same sex. Distribute the animals in at least seven equal groups of a number appropriate to the requirements of the assay.

      Determination of potency of the vaccine to be examined Using saline TS containing the aluminium adjuvant used for the vaccine or another appropriate diluent, prepare at least three dilutions of the vaccine to be examined and matching dilutions of the reference preparation. Allocate the dilutions one to each of the groups of animals and inject intraperitoneally not more than 1.0 ml of each dilution into each animal in the group to which that dilution is allocated. One group of animals remains unvaccinated and is injected intraperitoneally with the same volume of diluent. After an appropriate time interval (for example, 4 to 6 weeks), anaesthetize and bleed the animals, keeping the individual sera separate. Assay the individual sera for specific antibodies against HBsAg by a suitable immunochemical method (Appendix 14.5).

      Calculations Calculations are carried out by the “Statistical Analysis of Results of Biological Assay and Test” (Quantal response, Appendix 9).

      From the distribution of reaction levels measured on all the sera in the unvaccinated group, the maximum reaction level that can be expected to occur in an unvaccinated animal for that particular assay is determined. Any response in vaccinated animals that exceeds this level is by definition a seroconversion.

      Make a suitable transformation of the percentage of animals showing seroconversion in each group (for example, a probit transformation) and analyze the data according to a parallel-line log dose-response model. Determine the potency of the test preparation relative to the reference preparation.

      Validity conditions The test is not valid unless: 

      – for both the test and the reference vaccine, the ED₅₀ lies between the smallest and the largest doses given to the animals,

      – the statistical analysis shows no significant deviation from linearity or parallelism,

      – the confidence limits (P = 0.95) are not less than 33 per cent and not more than 300 per cent of the estimated potency.

      Potency requirement The upper confidence limit (P = 0.95) of the estimated relative potency is not less than 1.0.

      IN VITRO ASSAY

      Carry out the “Immunochemical Method” (Appendix 14.5) for determination of antigen content with acceptance criteria validated against the in vivo test.

      Enzyme-linked immunosorbent assay (ELISA) and radio-immunoassay (RIA) using monoclonal antibodies specific for protection-inducing of HBsAg have been shown to be suitable. Suitable numbers of dilutions of the vaccine to be examined and the reference preparation are used and a parallel-line model is used to analyze the data which may be suitably transformed. Kits for measuring HBsAg in vitro are commercially available and it is possible to adapt their test procedures for use as an in vitro potency assay.

      The acceptance criteria are approved for a given reference preparation by the competent authority in the light of the validation data.