Guideline for Bioequivalence Studies of Generic products


(Druft ver. 6:96July 1)

This guideline has been prepared by The Bioequivalence Test Committee established by the Ministry of Health and Welfare, Japan. Submit written comments on this guidance by December 31, 1996 to Nobuo Aoyagi, Ph.D, National Institute of Health Sciences (Fax: +81-3-3707-6950, E-mail: aoyagi@nihs.go.jp ) or Jun Yoshida, Pharmaceuticals and Cosmetic Division, the Ministry of Health and Welfare (Fax: +81-3-3597-9535).


Index

Section 1: Introduction

Section 2: Terminology

Section 3: Tests

A. Immediate release dosage forms

  1. Reference and test products
  2. Bioequivalence studies
    1. Test methods
        1) Design
        2) Number of subjects
        3) Selection of subjects
        4) Drug administration
        1. Dose
        2. Single vs. multiple dose studies
          1. Single dose studies
          2. Multiple dose studies
        5) Measurement of drug substances
           
        1. Biological fluids to be sampled  
        2. Sampling frequency and time  
        3. Drug substances to be measured  
        4. Assay
        6) Washout period
    2. Assessment of bioequivalence
        1) Parameters to be assessed
        2) Logarithmic transformation
        3) Statistical analysis
        4) Acceptance criteria
  3. Pharmacodynamic studies
  4. Clinical studies
  5. Dissolution tests
    1. Number of units tested
    2. Testing conditions
        1) Products containing acidic drugs
        2) Products containing neutral or basic drugs and coated products
        3) Products containing low solubility drugs
        4) Enteric coated products
    3. Acceptance criteria of equivalence of dissolution
  6. Reporting of test
    1. Samples
    2. Results
        1) Summary
        2) Dissolution tests
        3) Bioequivalence studies
        4) Pharmacodynamic studies
        5) Clinical studies
B. Controlled release dosage forms
  1. Oral controlled release dosage forms
    1. Reference and test products
        1) Reference products
        2) Test products
    2. Bioequivalence studies
        1) Test methods
        2) Assessment of bioequivalence
        3) Acceptance criteria
    3. Pharmacodynamic studies and clinical studies
    4. Reporting of test results
  2. Non-oral controlled release dosage forms
C. Dosage forms exempted from equivalence studies

Appendix. List of abbreviations of parameters


Section 1: Introduction

   This guideline describes the principle of procedures for bioequivalence studies of generic products. The objective of bioequivalence studies is to assure therapeutic equivalence of generic products to innovator's products. In bioequivalence studies, bioavailability should be compared between innovator's and generic products. If this is not feasible, pharmacological effects supporting efficacy or therapeutic effectiveness should be compared (these comparative tests are hereafter called pharmacodynamic studies and clinical studies, respectively). For oral drug products, dissolution tests should be performed, since they provide important information concerning bioequivalence.

Section 2: Terminology

Terms used in the guideline are defined as follows:

  1. Bioavailability: The rate and extent of absorption of parent drugs or active drug ingredients from a dosage form into the systemic circulation
    1. Absolute bioavailability: Ratio of the bioavailability of a drug product against that after intravenous injection.
    2. Relative bioavailability: Ratio of bioavailabilities of two drug products.
  2. Bioequivalent products: Drug products having the same bioavailabilities.
  3. Therapeutic-equivalent products: Drug products having the same therapeutic efficacies.
  4. Innovator's products: Products being approved as new drugs by clinical trials, or relevant drug products. If they cannot be specified or are unavailable, products approved before October, 1967 can be used. For JP drug products, leading products in the market can be used.
  5. Generic products: Products whose active ingredients, contents, dosage forms and regimen are the same as those of innovator's products.

Section 3: Tests

A. Immediate release dosage forms

I. Reference and test products

Dissolution tests (Sec. 3.A.V.) should be performed for three lots of an innovator's product. A lot which shows intermediate dissolution under the condition where the dissolution difference between the fastest and slowest lots is the largest should be selected as a reference product. For dosage forms which the dissolution tests cannot be applied to or are unsuitable for, alternative appropriate dissolution tests or physicochemical tests can be performed, and a product showing intermediate characteristic should be selected as a reference product. As a test product, it is recommended that generic products of industrial scale be used as lots. However, a lot no less than 1/10 of industrial scale can also be used as a test product and should not differ from the production lots in terms of manufacturing method, quality and bioavailability.

II. Bioequivalence studies

1. Test methods
An appropriate study protocol including the required number of subjects and sampling intervals should be determined according to preliminary studies and previously reported data.

  1. )Design:
    Crossover methods should be employed except for drugs with extremely long half-lives, for which parallel designs can be used.
  2. )Number of subjects:
    A sufficient number of subjects for assessing bioequivalence should be involved. If the bioequivalence cannot be demonstrated because of insufficient subject numbers, additional studies are acceptable.
  3. ) Selection of subjects:
    Bioequivalence studies should generally be performed with healthy volunteers. For drugs with potent pharmacological action, marked adverse effects or side effects, patients already under the drug treatment may be employed.
    Subjects with low gastric acidity are required in cases where the average dissolution percent of a slower dissolution product is less than 50% at the time when the average dissolution of a faster dissolution product reaches 80% in water or neutral test solution. However, this rule is not applied to rapidly dissolving products when more than 85% of the drug dissolves from both products in water or neutral test solution. For basic drugs for which dissolution tests cannot be conducted using water or neutral solution because of low solubility, selection of subjects should be based on the results obtained at around pH 3-5.
    If clearance of drugs largely differs among subjects due to genetic polymorphism, it is recommended that subjects with higher clearance be employed.
    If the use of drugs is limited to a special population, and dissolution profiles differ significantly between reference and test products, bioequivalence studies with subjects of the population may be needed.
    Before, during and after studies, close attention should be paid to a subjects' health condition, which should be recorded. In particular, during studies, the incidence of side effects and adverse effects should be closely monitored.
  4. )Drug administration:
    1. Dose: One dose unit or a clinical usual dose should generally be given. When a higher dose is employed due to analytical difficulties or other reasons, close attention should be paid to the subject's safety.
    2. Single vs. multiple dose studies: Single dose studies are generally employed except when multiple dose studies are preferable due to analytical difficulties such as low sensitivity or pharmacokinetic reasons such as large variability of clearance or non-linear elimination.
      1. Single dose studies: Drugs are usually given with 100-200 ml of water (normally 150 ml) after fasting for more than 10 hours. Fasting should continue for a further 4 hours after drug administration. If administration after a meal is prescribed in the dosing regimen, bioavailability under fasting conditions is markedly low, or a high incidence of severe adverse effects is indicated, drugs may be given postprandially. For a postprandial dose, the meal should be eaten within 15 minutes, and the drug administered according to the dosing regimen or 30 minutes.
      2. Multiple dose studies: Drugs should be administered under fasting conditions in principle as in the single dose studies when bioavailability is assessed. Before bioavailability assessment, drugs should be repeatedly given between meals (drugs should be administered more than 2 hours after a meal) at constant intervals. When postprandial administration is indicated or required, the drugs should be administered according to the dosing regimen or 30 minutes after the meal.
  5. )Measurement of drug substances
    1. Biological fluids to be sampled: Blood samples are generally used. Urine or saliva samples can be used instead of blood samples if appropriate.
    2. Sampling frequency and time: Blood or saliva samples should be taken at a frequency sufficient for assessing Cmax, AUC and other parameters. There should be at least 7 sampling points, including zero time, 1 point before Cmax, 2 points around the Cmax and 3 points during the elimination phase. Sampling should be continued until AUCt is over 80% of AUC (normally more than 3 times the elimination half life after tmax). When the elimination half life is extremely long, biological fluids should be collected for at least 72 hours.
      When urine samples are used, they should be collected in the same manner as blood samples.
      If F is determined by deconvolution, such extended sampling may not be required.
    3. Drug substances to be measured: Parent drugs or major pharmacologically active substances should be measured. When active metabolites are measured, the parent drug also should be measured as much as possible. Stereoselective assay is not generally required; however, when there exists stereoisomers which contribute different activities to the main pharmacological effect, and stereoselective absorption or elimination dependent on the absorption rate is noticeable, the enantiomer with higher activity should be measured.
    4. Assay: Analytical methods should be fully validated concerning specificity, accuracy, precision, linearity, quantitation limit, and stability of substances in samples.
  6. )Washout periods
    Washout periods in crossover studies between administration of test and reference products should usually be more than 5 times the elimination half life of the parent drug or active metabolites.

2. Assessment of bioequivalence
  1. ) Parameters to be assessed
    When blood or saliva samples are used, AUCt and Cmax should be subjected to the bioequivalence assessment in single dose studies. For multiple dose studies, AUC and Cmax are used. Cmax is an observed value and AUC is calculated using the trapezoidal integration method. If F can be estimated by deconvolution, F can be used for AUC.
    Parameters such as AUC, tmax, MRT and kel should be submitted as reference data. For multiple dose studies, C also is used as a reference parameter.
    When urine samples are used, Aet and Umax should be employed for assessment.
    The contents or potencies of test and reference products should not differ by more than 5%. If the content or potency of a reference product deviates from the claimed value by more than 5%, parameter values of the reference product should be normalized for the dose.
  2. )Logarithmic transformation: AUC and Cmax (Aet, Umax) should generally be statistically analyzed after logarithmic transformation. Analyzed data using values without transformation are also submitted. Tmax is usually not transformed.
  3. )Statistical analysis
    The 90% shortest confidence interval or two one-sided t tests with significance levels of 5% should be used. Other reasonable statistical methods also can be used.
  4. )Acceptance criteria
    The 90% confidence interval of average AUC and Cmax (Aet and Umax) of test products should be within the acceptable range from 80% to 125% of average values of reference products. For drugs with pharmacologically mild action, however, a wider acceptable range may be applicable to Cmax (Umax).
    Reference parameters should be subjected to statistical assessment. If a significant difference is detected in the reference parameters between reference and test products, an explanation of the effects of this difference on the therapeutic equivalence is required.
    In addition, test products are accepted as bioequivalent products, when dissolution rates of reference and test products are evaluated to be equivalent under all the conditions of the dissolution tests (Sec.3 A.V), and when averages of AUC and Cmax (Aet and Umax) of the test products are within 90-111% of those of the reference products, even though the confidence interval does not meet the above criteria estimated by the study using 10 subjects or more per group. However, this rule cannot be applied to slowly dissolving products from which more than 80% of a drug does not dissolve within 6 hours under any conditions of the dissolution tests described in Sec.3 A.V.

III. Pharmacodynamic studies

These studies are performed to establish the equivalence of products using pharmacological activity in humans as an index. This is applied to pharmaceuticals which do not produce measurable concentrations in accessible biological fluids and those in which bioavailability does not reflect therapeutic effectiveness (topical drug products without intended absorption).
Animal tests are allowed for topical drugs (skin, digestive tract, and etc.) with mild pharmacological effects and whose equivalence is hard to demonstrate in humans.
Acceptance criteria may vary depending on the efficacy of the drugs and therapeutic concentration ranges.

IV. Clinical studies

These studies are performed to establish the equivalence of drugs using clinical effectiveness as an index. If bioequivalence studies and pharmacodynamic studies are impossible or inappropriate, this study is applied.
Acceptance criteria may vary depending on the efficacy of the drugs and therapeutic concentration ranges.

V. Dissolution tests

Dissolution tests described in this chapter are basically applied to solid oral dosage forms. For other dosage forms alternative suitable dissolution tests may be employed.

1. Number of units tested: 6 units should be used under each testing condition.

2. Testing conditions:
The test is proceeded under the following conditions. If the test cannot be done under these conditions, or there are more appropriate conditions, the testing conditions can be changed or modified.

Apparatus: JP paddle apparatus
Volume of test solutions: Usually 900 ml
Test solutions: The 1st and 2nd fluids (disintegration test, JP13) can be used as pH 1.2 and 6.8 test solutions, respectively, and McIlvaine buffers (pH is adjusted with 0.05M monobasic sodium phosphate and 0.025M citric acid) can be used for other pHs. For the dissolution specification, other test solution may be employed.
  1. ) Products containing acidic drugs
    Agitation(rpm)  pH
    50 A 1.2
    B 5.5 - 6.5a)
    C 6.8 - 7.5 a)
    D Water
    100 B,C or Da)
     a) The testing solution providing the slowest dissolution among the test solutions which give more than 80% of dissolution within 6 hours should be selected.

  2. ) Products containing neutral or basic drugs, and coated
    Agitation(rpm) pH
    50 A 1.2
    B 3〜5 a)
    C 6.8
    D Water
    100 B,C or Da)
    a) The testing solution providing the slowest dissolution among the test solutions which give more than 80% of dissolution within 6 hours should be selected.

  3. )Products containing low solubility drugs
    When reference products do not provide more than 80% dissolution on average at 6 hour under any of the testing solutions without surfactants, they are defined as products containing low solubility drugs.
    Agitation(rpm)  pH Surfactants
    50 A 1.2 appropriate surfactants a)
    B 4 appropriate surfactants
    C 6.8 appropriate surfactants
    D Water appropriate surfactants
    100 C or Db) appropriate surfactants a)
    a) The lowest surfactant concentration providing more than 80% of dissolution within 6 hours
    b)The test solution providing slower dissolution which gives more than 80% of dissolution within 6 hours should be selected.

  4. )Enteric coated products
    Agitation(rpm)  pH
    50 A 1.2
    B 6.0
    C 6.8
    D Water
    100 B

3. Acceptance criteria of equivalence of dissolution profiles
Average dissolution rates of test products should be compared with those of reference products. If the results meet either of the following criteria in all testing conditions, the products are judged to be equivalent. Equivalence in the dissolution rates does not necessarily mean bioequivalence.

Case 1. More than 85% of the drug dissolves within 15 minutes from all samples of reference and test products.

Case 2. More than 80% of the drug on average dissolves from the reference product within 30 minutes and the average dissolution percent of the test product does not deviate by more than 15% from that of the reference product at the time point when the average dissolution percent of the reference product is around 70-80%.

Case 3. When average dissolution lag time* of reference products is longer than 15 minutes, and tests and reference products meet either (a) or (b). (a) More than 85% of the drug dissolves within 15 minutes after the lag time from all samples of reference and test products, and the difference in the averages of the dissolution lag times between the two products must be less than 10 minutes. (b) More than 80% of the drug on average dissolves from the reference product between 15-30 minutes after dissolution lag time, and the average dissolution percent of the test product does not deviate by more than 15% from that of the reference product at the time point when the average dissolution percent of the reference product is around 70-80%. In addition, the difference in average dissolution lag times between the two products is less than 10 minutes.
* Dissolution lag time is defined as the time required for 5% of the drug to dissolve.

Case 4. The average dissolved percent from test products does not deviate by more than 15% from that of the reference product at two time points when average dissolved amounts from reference products are around 40% and 80%,.

Case 5. When the average dissolution percent of reference products does not reach 80% at 6 hour, the average dissolved amount from test products does not deviate by more than 15% from that of the reference product at the time point(s) when the average dissolved amount from reference products is around 40%, and/or at 6 hours,.

VI. Reporting of test

1. Samples

  1. )Brand name and lot No.
  2. )Type of dosage forms
  3. )Name of drug substances
  4. )Labeled contents
  5. )Measured contents and assay procedures
  6. )Solubility of drugs (Solubility at different pHs
  7. )For the case of low solubility drugs, particle size or specific surface area and their measurement procedures
  8. )Types of polymorphs and solubility
  9. )Others (For example, pka and physicochemical stability)

2. Results of tests
  1. )Summary
  2. )Dissolution tests:
    1. List of test conditions (apparatus, stirring speed, types and volumes of test solutions)
    2. Analytical method
    3. Results
      1. Results of preliminary tests performed to select one lot of reference products.
        Tables listing dissolution percent of individual samples under each testing condition, average values and standard deviations of each lot.
        Figures Comparing average dissolution curves of each lot under each testing condition
      2. Comparison of reference and test products
        Tables listing dissolved amounts of individual samples under each testing condition, the average values and standard deviations of test and reference products.
        Figures comparing average dissolution curves of test and reference products under each testing condition.
  3. ) Bioequivalence studies
    1. Experimental conditions Subjects: Age, sex, body weight and other items obtained by laboratory tests are described. Individual gastric acidity should be reported if necessary or available.
      Drug administration: fasting time, co-administered water volume, and times of drug administration and food ingestion after administration are described. In the case of postprandial administration, menu and content of meal (protein, fat, carbohydrate, calories and others), and times of food ingestion during studies are included.
      Assay: Calibration curves, accuracy, precision, specificity, quantitation limit, the stability of analytes in samples and so forth.

    2. Results
      1. Data of individual subjects
        Tables showing drug levels in biological fluids at each sampling point, Cmax (Umax), Ctau (Utau ), AUCt (Aet), AUCtau (Aetau ), AUCinf (Aeinf ), tmax and MRT. In addition, kel and the correlation coefficient together with time points used for their calculation should be reported.
        The ratios of Cmax and AUCt (Umax, Aet), of test products to those of reference products should be reported.
        Figures comparing individual drug level-time profiles of the two products drawn on a linear/linear scale.
      2. Averages and standard deviations
        Tables showing averages and standard deviations of drug levels in biological fluids at each time point, Cmax (Umax Ctau (Utau ), AUCt (Aet), AUCtau (Aetau ), AUCinf (Aeinf ), kel, tmax and MRT.
        The ratios of averages of Cmax, AUCt (Umax, Aet), of test products to those of reference products should be reported.
        Figures comparing average drug level-time profiles of the two products drawn on a linear/linear scale.
      3. Statistical analysis and equivalence assessment
        Analysis of variance tables, the 90% confidence intervals, the required number of subjects for the confidence interval method and power based on the power approach should be described for Cmax (Umax), Ctau (Utau ), AUCt (Aet), AUCtau (Aetau ), AUCinf (Aeinf ), tmax, MRT, kel and other parameters.
      4. Analysis of pharmacokinetic parameters If deconvolution is used, the program used, algorithm, pharmacokinetic models and information about their suitability should be listed.
      5. Others Information on drop-outs (data, reasons), observation records of the health of subjects.
  4. )Pharmacodynamic studies
      Reporting results should follow that of bioequivalence studies.

  5. ) Clinical studies
      Reporting results should follow that of bioequivalence studies.

B. Controlled release dosage forms

I. Oral controlled release dosage forms

1. Reference and test products

  1. )Reference products
    Dissolution tests (Sec.3 A.V) should be performed for three lots of an innovator's product. A lot which shows intermediate dissolution under the condition where the dissolution difference between the fastest and slowest lots is the largest should be selected as a reference product. 
  2. )Test products
    A generic product of controlled release dosage forms should not significantly differ from the reference product in shape, weight and releasing mechanisms. The lot size should be the same as that of immediate release products. The dissolution characteristics of test products must be similar to those of reference products. That is, the average dissolution percent of test products must not deviate by more than 15% from that of reference products under any of the following conditions at 3 time points when average dissolution percents of reference products are around 30%, 50% and 80%.
    1. Number of units tested: 6 units are used under each testing conditions.
    2. Testing conditions: Dissolution tests should be conducted under the following conditions. The other details should follow the dissolution tests described before. Either the rotating basket or disintegration testing apparatus or both can be used. If the dissolution tests are impractical, or there exist more appropriate conditions, alternative tests or testing conditions are acceptable.
      Apparatus rpm  pH Others
      1 Paddle 50 A 1.2
      B 3 - 5
      C 6.8 - 7.5
      D Water
      C or D Appropriate detergents a)
      100 C orD
      200 C or D
      2 Rotating basket100
      200 C or D
      3 Disintegration test apparatus 30 C or Dwithout disks
      30 C or Dwith disks
      a) For example, 0.2% polysorbate
2. Bioequivalence studies

  1. )Test Methods
    Bioequivalence analysis should be performed by single dose studies in both a fasting and fed state. Multiple dose studies should be employed when they are considered to be more suitable due to analytical difficulties such as low sensitivity, or pharmacokinetic reasons such as large variability of clearance or non-linear elimination. In the case of postprandial administration, it is recommended that eating be completed within 15 minutes, and drugs be administered within 10 minutes after eating. Study design, the number of subjects, selection of subjects and observation of health, administration conditions, dose, drug administration, biological fluids collected, sampling frequency and time, drug substances to be measured, assay, and washout period should follow those of immediate release dosage forms.
  2. )Assessment of bioequivalence
       Parameters and statistical analysis methods are the same as those of immediate release dosage forms.
  3. )Acceptance criteria
    The 90% confidential interval of averages of AUC (Ae) and Cmax (Umax) of test products should be within the acceptable range of 80-125% of those of reference products. For drugs with pharmacologically mild action, however, a wider acceptable range may be applicable to Cmax (Umax). In addition, test products are accepted, when their average dissolution percent does not deviate by more than 10% from those of reference products at three time points as specified in Sec.3.B.I.1-2, under any of the testing conditions, and when averages of AUC and Cmax (Aet and Umax) are within 90-111% of those of the reference products, even though the confidence interval does not meet the above criteria estimated by the study using 10 subjects or more per group.

3. Pharmacodynamic studies and clinical studies

If bioequivalence studies cannot be performed, pharmacodynamic or clinical studies should be carried out to evaluate equivalence. The tests proceed in accordance with immediate release dosage forms.

4. Reporting of test results

Reporting should be the same as that of immediate release dosage forms.

II. Non-oral controlled release dosage forms

Tests should proceed in accordance with the standards for oral controlled release dosage forms. Appropriate tests should be chosen and done taking into consideration characteristics of dosage forms.

C. Dosage forms exempted from equivalence

 Intravenous aqueous solutions when use.


Appendix List of abbreviations of parameters

Aet Cumulative amounts excreted in the urine from zero to the final sampling
Ae inf Cumulative amounts excreted in the urine from zero to infinity
AUC Area under drug concentration in blood (saliva)-time curves
AUCt AUC from zero to the final sampling time t
AUCtau AUC over one dose interval at steady-state
AUCinf AUC from zero to infinity
Cmax The maximum drug concentration in blood (saliva)
Ctau Trough drug concentration in blood (saliva)
(drug concentration in blood (saliva) at the last sampling time at steady- state)
F Extent of bioavailability (Absorbed fraction)
kel Elimination rate constant
MRT Mean residence time
tmax Time to maximum drug concentration in blood (saliva) or time to maximum urinary excretion
Umax The maximum urinary excretion rate
Utau Trough urinary excretion rate
(urinary excretion rate at the last sampling time at steady-state)


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