the international pharmacopoeia quality standards for tb medicines caroline mendy - technical...

The International Pharmacopoeia

Quality standards for TB medicines

Caroline Mendy - Technical Officer - Quality Assurance and Safety: Medicines

Tutorial workshop, Beijing, March 2010

2 | Tutorial workshop, Beijing, March 2010

Quality standards for TB medicines – an issue?

Quality standards for TB medicines – an issue?

"[…] reliable quality of medicines is absolutely essential for effective TB programmes"

TB Alliance

"[…] low quality drugs damage patient recovery and increase the likelihood of drug-resistant strains of TB

Stop-TB partnership

Several WHO studies carried out or on-going to monitor the quality of marketed TB medicines


Quality standards for TB medicinesQuality standards for TB medicines

1. Monographs available in Ph.Int.

2. Monographs, requirements and identity tests

3. Assay and related substances– method development

4. Dissolution / disintegration specifications– Isoniazid and Ethambutol hydrochloride tablets

Focus: TB FDC tablets


Ph.Int. TB monographsPh.Int. TB monographs

Priorities for inclusion of new specifications for TB medicines:

WHO Essential medicines lists

WHO specific disease programmes (e.g. Stop-TB, Prequalification)

Specifications for first-line and second-line TB drugs available (APIs and FPP)


Ph.Int. TB monographsPh.Int. TB monographs

Amikacin (revision) - Oct 2009

Amikacin sulfate (revision) - Oct 2009

Amikacin injection - Oct 2009

kanamycin monosulfate - Oct 2009

kanamycin acid sulfate - Oct 2009

Kanamycin injection - Oct 2009

Isoniazid

Isoniazid tablets

Pyrazinamide

Pyrazinamide tablets

Rifampicin

Streptomycin sulfate

Streptomycin sulfate powder for injection

Thioacetazone

Cycloserine

Cycloserine capsules

Ethambutol HCl (revision)


Ph.Int. TB monographs – to come…Ph.Int. TB monographs – to come…

Capreomycin - draft in progress

Capreomycin injection - draft in progress

Ethionamide tablets*

Protionamide tablets*

Terizidone*

Ofloxacin tablets*

Levofloxacin tablets*

p-aminosalicylic acid granules/tablets*

*on 2010 work programme


Ph.Int. monographs: TB FDC dosage formsPh.Int. monographs: TB FDC dosage forms

4FDC: Rifampicin / Isoniazid / Pyrazinamide / Ethambutol HCl tablets

3FDC: Rifampicin / Isoniazid / Pyrazinamide tabletsRifampicin / Isoniazid / Pyrazinamide dispersible tablets (new)Rifampicin / Isoniazid / Ethambutol HCl tablets (new)

2FDC: Rifampicin / Isoniazid tabletsRifampicin / Isoniazid dispersible tablets (new) Isoniazid / Ethambutol HCl tablets

Rifampicin tabletsRifampicin capsules

Basic approach for monograph development: top down

9 monographs!


Ph.Int. monographs: TB FDC dosage formsPh.Int. monographs: TB FDC dosage forms

Strategy– Start with the most complex combination (4FDC tablets)– Work down to most simple situation using same procedures

Rifampicin

Ethambutol

Isoniazid

Pyrazinamide

4FDC

3FDC

2FDC


TB 4FDC tabletsPh.Int. monograph: Information section

TB 4FDC tabletsPh.Int. monograph: Information section

√

?

√


TB 4FDC tabletsMonograph: Requirements


√

√

?

read General monograph for Tablets


TB 4FDC tabletsMonograph: Identity tests


Requirement:

Specific for each API in the 4FDC tablet– identification should be conclusive on presence / absence of

the APIs

1. More than one test may apply for conclusive identification– tests X and Y

2. There may be a choice between tests– either test X or test Y may be applied

read instruction in monograph carefully




The TB 4FDC monograph states the following:

Either tests A and B or test C may be applied

Tests A and B are the 2 HPLC assay tests– retention time compared to ICRS (reference substance)

Test C is a TLC test– position (Rf), appearance & intensity of spot compared to ICRS

• note 3 parameters in one test– Choice with respect to visualisation of spots

• UV or visible (after exposure to iodine vapour)Test C first


TB 4FDC tabletsMonograph: Identity test (copy from monograph)

TB 4FDC tabletsMonograph: Identity test (copy from monograph)

HF254


TB 4FDC tabletsMonograph: Identity test (results)

TB 4FDC tabletsMonograph: Identity test (results)

Eth INH PY Rif Tab

In UV (254 nm),before exposure to I2

Method C.2In daylight,

after exposure to I2

Method C.1In UV (254 nm),

after exposure to I2


Structures of the APIs in TB 4FDC tabletStructures of the APIs in TB 4FDC tablet

Rifampicin

Isoniazid

Pyrazinamide Ethambutol

UV absorbing groups?

YesYes

YesNo


TB 4FDC tabletsMonograph: Related substances

TB 4FDC tabletsMonograph: Related substances

General recommendation for FDCs

Related substances (degradation products) should be tested in the FDC products for

– APIs which are unstable– Very stable APIs may not be required

What is the situation in the case of the TB 4FDC tablets?– Consult literature for stability– Do stress testing under various conditions (part of validation)

• Temperature, pH, oxidation, light, …• API-API interactions


Information from literature & structure Rifampicin

Information from literature & structure Rifampicin

oxidation(to N-oxide)

light sensitive

oxidation(to quinone)

hydrolysis(to 3-formyl rifamycin)

hydrolysis (to 25-desacetyl)

quinone


Information from literature & structure 3-Formyl rifamycin

Information from literature & structure 3-Formyl rifamycin

o

+ H2N ― R

R Isoniazid


Information from literature & structure “isonicotinoyl hydrazone”

Information from literature & structure “isonicotinoyl hydrazone”

o

N ― R

R Isoniazid


Information from literature & structure Rifampicin - summary

Information from literature & structure Rifampicin - summary

Rifampicin known degradation products

Oxidation– Rifampicin quinone– Rifampicin N-Oxide

Hydrolysis– 3-Formyl rifamycin– 25-desacetyl rifampicin

Reaction with Isoniazid– isonicotinoyl hydrazone

• 3-(isonicotinoylhydrazinomethyl)rifamycin

light sensitive


Information from literature & structureRifampicin

Information from literature & structureRifampicin

Special storage conditions for the API?

International Pharmacopoeia:

Rifampicin should be kept in– a tightly closed container

• (exclude exposure to air - moisture and oxygen)– (container of low permeability)

– protected from light and– stored at a temperature not exceeding 15°C, or– in an atmosphere of nitrogen at a temperature not exceeding

30°C• (absence of air oxygen)


Rifampicin impurities (TLC)Rifampicin impurities (TLC)

Reference: Int.Ph. related substances test for rifampicin

• Silica gel R1

• CHCl3/methanol : 85/15

• Daylight detection

a Rifampicin test substance: 20 mg/ml

b Quinone: 0.8 mg/ml (4.0%)

c N-oxide: 0.3 mg/ml (1.5%)

d 3-Formyl rifamycin: 0.1 mg/ml (0.5%)

e Rifampicin: 0.2 mg/ml (1.0%)

a b c d e


Information from literatureIsoniazid

Information from literatureIsoniazid

Small molecule– Quite stable– Can hydrolyze under stress conditions to inter alia

isonicotinic acid & hydrazine– Primary amine - react with aldehydes, for example

• reducing sugars / lactose• 3-Formyl rifamycin (rifampicin degradation product)


Information from literaturePyrazinamide

Information from literaturePyrazinamide

Small molecule– Quite stable– Amide group can hydrolyse under strong conditions to

pyrazinoic acid & ammonia

Test D in Ph.Int. monograph for Pyrazinamide API:– Boil 20 mg with 5 ml of sodium hydroxide (~200 g/l) TS;

ammonia, perceptible by its odour, is evolved.


Information from literatureEthambutol hydrochlorideInformation from literatureEthambutol hydrochloride

Small molecule

Quite stable• (2-aminobutanol – synthesis impurity)

Hygroscopic (solubility in water: 50% m/m)– In FDC tablets ethambutol can absorb water

• absorbed water helps degradation of rifampicin

Forms metal complexes– Very useful in FDC assay test

S,S-isomer pharmaceutical

:N—C│

:N—CCu++


Information from literatureWhat is important for monograph development?

Information from literatureWhat is important for monograph development?

Rifampicin related substances to be tested for– Rifampicin quinone– Rifampicin N-Oxide– 3-Formyl rifamycin– isonicotinoyl hydrazone = product with isoniazid– 25-desacetyl rifampicin

Protect from light (mainly due to rifampicin)– Product (packaging) and sample / test solutions

Protect from moisture– “Manufacture” ► protective packaging + set moisture limit– QC testing ► protect tablet powder from moisture uptake


TB 4FDC tabletsExamples of water uptake

TB 4FDC tabletsExamples of water uptake

FPPs (packed products)

Unpacked tablets (control)

After 5 days at 40°C/75% RH

After 5 days at 40°C/75% RH + Light

S. Singh, Int. J. Tuberc. Lung. Dis., 7, 298 (2003)

ProductsB A

Quality of the products not known

“bleeding”


TB 4FDC tabletsExample of poor FPP

TB 4FDC tabletsExample of poor FPP

Have you seen a TB 4FDC tablet like this when opening the primary packaging?

Hopefully not

Example: TB 4-FDC tablets– one year from expiry

Photo from:

S. Singh & B. Mohan, Int. J. Tuberc. Lung. Dis., 7, 298 (2003)




√

√

?

read General monograph for Tablets

√


TB 4FDC tabletsAssay and related substances

TB 4FDC tabletsAssay and related substances

The objectives

1. To develop assay methods for– all four APIs in the TB 4FDC tablet– HPLC as only option

2. To develop methods for determination of degradation products (related substances)– Only for rifampicin– HPLC as only option


Assay TB 4FDC tabletsAssay and related substances


The approach to HPLC methods

1. Minimise the number of HPLC methods– Not 4 HPLC methods for assay of the 4 APIs

2. The column(s) should be easily obtainable

3. The use of an isocratic profile instead of a gradient profile– the test can be carried out by any laboratory

4. The assay method(s) should be stability-indicating

5. It would be advantageous if the related substances could be determined with the method(s) used for assay




Strategy followed

1. Screening of existing methods– Literature– Manufacturers

2. Selecting promising candidates– Desk and experimental evaluation

3. Optimisation of selected method(s)

4. Validation




The outcome

Two HPLC methods have been developed

1. One method for simultaneous assay of one or more of– Isoniazid– Pyrazinamide– Ethambutol hydrochloride

2. Another method for rifampicin– Assay– Related substances (degradation products)


Assay TB 4FDC tablets Isoniazid/Pyrazinamide/Ethambutol HPLC

Assay TB 4FDC tablets Isoniazid/Pyrazinamide/Ethambutol HPLC

Ethambutol properties were key to assay method

Problem– Ethambutol lacks useful absorption in UV/visible region

• USP method - detection at 200 nm

Answer– Ethambutol compexes with Cu2+

• Maximum absorption at 270-280 nm

Method principle– Copper(II) acetate in mobile phase


Assay TB 4FDC tabletsIsoniazid/Pyrazinamide/Ethambutol HPLC


min0 1 2 3 4 5 6 7 8 9

mAU

0

200

400

600

800

1000

1200

1400

DAD1 A, Sig=270,4 Ref=360,100 (AMR_EA\27070419.D)

1.7

55

-

Iso

nia

zid

2.1

93

-

Py

raz

ina

mid

e

5.7

53

-

Eth

am

bu

tol H

Cl

Ison

iazi

dP

yraz

inam

id

Eth

ambu

tol

10 min

Cu2+ in mobile phase

Detection at 270 nm

resolution ≥ 2

buffer pH 5.0




Validation

All parameters were validated– ICH Q2(R1)

Specificity of particular interest– No “innovator” product– Placebo constructed from all known excipients in 4FDC tablets

• information from package inserts– Stress testing

• water, alkali, acid, hydrogen peroxide at 40°C on one product– DAD (Diode Array Detection) for peak purity


Assay / related substances TB 4FDC tabletsRifampicin HPLC

Assay / related substances TB 4FDC tabletsRifampicin HPLC

Rifampicin related substances to be tested for

Rifampicin quinone

Rifampicin N-Oxide

3-Formyl rifamycin

3-(isonicotinoylhydrazinomethyl)rifamycin– "hydrazone“ obtained from 3-formylrifamycin & isoniazid reaction– Sample donated by Dr S. Singh, NIPER, India

25-desacetyl rifampicin

Also applicable to:– 3FDC, 2FDC tablets and rifampicin tablets and capsules


Assay / related substances TB 4FDC tabletsRifampicin HPLC – Isonicotinoyl hydrazoneAssay / related substances TB 4FDC tabletsRifampicin HPLC – Isonicotinoyl hydrazone

In situ preparation of– 3-(isonicotinoylhydrazinomethyl)rifamycin

• hydrazone formed from rifampicin and isoniazid reaction– solution (5)

For solution (5) dissolve 4 mg of rifampicin RS and 2 mg of isoniazid RS in 25.0 ml of acetic acid (~60g/l) TS and keep the solution at room temperature for 30 minutes

Rationale of in situ preparation based on molecules structures/interactions


Assay TB 4FDC tablets Rifampicin HPLC

Assay TB 4FDC tablets Rifampicin HPLC

Validation

All parameters were validated– ICH Q2(R1)

Specificity of particular interest– No “innovator” product– Placebo constructed from all known excipients in 4FDC tablets

• information from package inserts– Known impurities & validation– Stress testing

• water, alkali, acid, hydrogen peroxide at 40°C on one product– DAD (Diode Array Detection) for peak purity


Dissolution / disintegration specificationsBCS


The Biopharmaceutics Classification System (BCS) of an API is based on its

– aqueous solubility and– intestinal permeability

According to the BCS an API falls in one of four classes:

ClassSolubilityPermeability

1HighHigh

2LowHigh

3HighLow

4LowLow




High solubility definition

The highest single unit dose of an API is completely soluble in 250 ml or less of aqueous medium over the pH range 1.0 - 6.8 (at 37°C)

No relevance to Ph.Int. solubility definitions, e.g. diazepam– Ph.Int.

• Very slightly soluble (1 gram in 1000 to10 000 ml of water at 20°C)– BCS

• High solubility (5 mg in ≤ 250 ml at 37°C)




Classification of TB APIs

WHO Technical Report Series 937, Annex 8 (2006)

APIClassSolubility

Rifampicin(300 mg)

2Low

Isoniazid(300 mg)

3/1High

Pyrazinamide(400 mg)

3/1High

Ethambutol 2HCl(400 mg)

3High


Dissolution / disintegration specificationsIsoniazid/Ethambutol tablets


Acceptance criteria

Either (A) Dissolution or (B) Disintegration may be applied

A. DissolutionAll 6 units ≥ 80% of label claim dissolved in 30 min.– If one tablet fails, average of 12 tablets ≥ 75%, none <60%

– Criteria as set at EC meeting of Oct. 2007

B. Comply with 5.4 Disintegration test for tablets and capsules, operating the apparatus for 10 minutes– If the tablets do not comply, carry out test A above– More stringent than dissolution test

Generally applicable to Class 1 & 3 APIs




Dissolution conditions of Ph.Int. for– Tablets/capsules containing a BCS

highly soluble API

– Samples analysed by HPLC method for assay

ApparatusPaddle, 75 rpm

Dissolution medium

pH 6.8 phosphate buffer

Volume of medium

500 ml

Degassed?No (undegassed)

Temperature37°C ± 0.5°C

Sampling points

10, 15, 20, 30, 45, and 60

4 products testedAPI: Isoniazid

0

20

40

60

80

100

120

0 10 20 30 40 50 60 70

Withdrawal time in minutes

Dis

so

luti

on

(%

)

4 products testedAPI: Ethambutol

0

20

40

60

80

100

120

0 10 20 30 40 50 60 70

Withdrawal time in minutes

Dis

so

luti

on

(%

)

A

C

D

B


Isoniazid/Ethambutol tabletsDiscussion of results

Isoniazid/Ethambutol tabletsDiscussion of results

1. The dissolution profiles of the 2 APIs in a particular product are similar (this is true for all 4 products)– Both APIs are highly soluble (BCS definition)

2. The products show different dissolution rates– Dissolution rate A > B ≈ C >> D– Disintegration (min) 7 11 11 21– Dissolution rate is related to disintegration time– Acceptance criteria: Disintegration tighter than dissolution

3. For BCS highly soluble APIs– The dissolution rate is controlled mainly by disintegration of

the tablets/capsules


Closing remarksClosing remarks

1. Approach for development of TB FDC tablet monographs– Top down (4FDC → 3FDC → 2FDC → rifampicin tabs/caps)– In this way all monographs can have same test methods

2. For rifampicin and rifampicin related substances– One HPLC method– Includes detection of isonicotinoyl hydrazone (API-API reaction)

3. For isoniazid, pyrazinamide & ethambutol hydrochloride– One method, no related substances

4. Dissolution/disintegration for isoniazid/ethambutol 2HCl tablets– Acceptance criteria: Disintegration tighter than dissolution– Ph.Int. takes lead with setting alternative criteria for

Class 1 & 3 API tablets/capsules


More information… More information…

Information extracted from

The International Pharmacopoeia

http://www.who.int/medicines/publications/pharmacopoeia/en/

WHO Prequalification: Training Material and workshops

International Pharmacopoeia – Development of monographs for tuberculosis fixed-dose combination tablets – Professor. T. Dekker

http://apps.who.int/prequal/


Thank you!

the international pharmacopoeia quality standards for tb medicines caroline mendy - technical...

Documents

tb fdc tablets

fdc tablets monograph

fdc slide

protionamide tablets

levofloxacin tablets

tb monographs priorities

medicines tutorial workshop

progress ethionamide