A COMPARATIVE STUDY ON THE IN VITRO
DISSOLUTION PROFILES OF COMMERCIALLY
AVAILABLE CLARITHROMYCIN ORAL DOSAGE
FORMS IN NAIROBI COUNTY, KENYA
By:Manani O. Rebecca
U59/81391/2012
Department of Pharmaceutical ChemistrySchool of PharmacyUniversity of Nairobi
November 13, 2014
OUTLINE
Introduction
Study justification
Study objectives
Methodology
Results and discussion
Conclusion
Recommendations
Acknowledgements2
INTRODUCTION: MACROLIDES
Natural and semi-synthetic antibiotics characterised by macrocyclic rings with attached sugars
Source: Streptomyces and micromonospora species
Classification
14– erythromycin, clarithromycin, roxithromycin
15 – semi-synthetic azalides: azithromycin, gamithromycin
16 – josamycin, spiramycin, rokitamycin3
MACROLIDES (CONT’D) Mode of Action
Inhibit protein synthesis; prevent transpeptidation Spectrum of Activity
G+ve: S. aureus, Str. pyogenes, Str. pneumoniae
G-ve: H. influenzae, N. meningitidis, H. pylori
Atypical: M. pneumoniae, C. trachomatis, Mycobacteria, Toxoplasma, Borrelia spp.
Limitations of Natural Macrolides
Acid instability, GIT side-effects, resistance, narrow spectrum
4
CLARITHROMYCIN
Chemistry
2nd generation semi-synthetic macrolide
5
O
CH3O
H3CHO
HO
H3CH5C2
O
CH3
CH3
OCH3
O
O CH3
OHOCH3H3C
OCH3
O CH3
NCH3H3C
HO
Clarithromycin
Erythromycin A
1
3
6
9
12
O
CH3O
H3CHO
HO
H3CH5C2
O
CH3
CH3
OH
O
O CH3
OHOCH3H3C
OCH3
O CH3
NCH3H3C
HO
5
STABILITY OF CLARITHROMYCIN
Oxidative; basic; acidic conditions6
O
CH3O
H3CHO
HO
H3CH5C2
O
CH3
CH3
OCH3OCH3
O CH3
NCH3H3C
HO
OH
Decladinosylclarithromycin
O
CH3O
H3C
HO
H3CH5C2
O
CH3
CH3
OCH3
O
O CH3
OHOCH3H3C
OCH3
O CH3
NCH3H3C
HO
10,11-Anhydroclarithromycin
9,12-Hemiketal
O
CH3
H3C
H3CH5C2
O
CH3
CH3
OCH3
O
O CH3
OHOCH3H3C
OCH3
O CH3
NCH3H3C
HO
O
O
CH3O
H3CHO
HO
H3CH5C2
O
CH3
CH3
OCH3
O
O CH3
OHOCH3H3C
OCH3
O CH3
NH3C
HO
CH3
O
Clarithromycin N-oxide
STUDY JUSTIFICATION Quality of drugs crucial in treatment outcomes Previous reports of poor quality products in 3rd
world countries Clarithromycin is in EML - Kenya, WHO BCS classification
Tablets – class II (Low aq. solubility, low permeability) Suspensions – class IV (Low aq. solubility, low
permeability) Generics used as a cost cutting measure No bioequivalence testing centres in Kenya No previous PMS studies on CLA in Kenya
7
STUDY OBJECTIVES
General Objective
To conduct comparative in vitro dissolution studies on oral clarithromycin products in Nairobi County
Specific Objectives
To carry out product sampling in Nairobi County
To carry out identification and assay tests
To carry out comparative dissolution testing – innovator, generics
To determine pharmaceutical equivalence 8
METHODOLOGY I: SAMPLING Study population – 125 mg/5 mL susp, 500 mg
tablets
Time frame – January to March 2014
Stocking patterns revealed uneven distribution
Sites –11 outlets in Nairobi, 1 in England, UK
16 samples – 12 tabs and 4 suspensions (67% stocking rate in Nairobi)
Sample size – 60 tablets and 500 mL suspensions 9
METHODOLOGY II: METHOD OPTIMIZATION
MOA – published method (Abuga et al. 2001)
Method optimization
Detection wavelength, Sample injection volume, Mobile phase flow rate
Quenching conditions - dissolution pH 1.2
Optimum conditions: mp - ACN-0.2 M phosphate buffer, pH 6.80-water (40:3.5:56.5, v/v/v), flow rate -1.5 mL/min, sp - XTerra RP C18, 5 m (250 mm x 4.6 mm ID), temp - 56 oC detection 205 nm, quenching – 3 mL of 0.2 M NaOH 10
METHOD OPTIMIZATION (CONT’D)
Fig.1 - Typical assay chromatogram for clarithromycin working standard under the optimum chromatographic conditions
11
0.0 5.0 10.0 15.0 20.0 min
-75
-50
-25
0
25
50
75
100
125
mAU205nm,4nm (1.00)
CLA
METHODOLOGY III: ASSAY AND DISSOLUTION
USP and BP methods for sample preparation
Tabs – uniformity of weight (BP), assay
Granules – RD, extraction (USP), assay
Dissolution carried out at pH 1.2, 4.5, 6.8
Run time - 60 min. tabs, 90 min. suspensions
6 sampling time points
Dissolution profiles generated and f2 factors calculated
f2= 50×log {[1+ (1/n) Σ t=1n (Rt-Tt) 2] -0.5 ×100} 12
RESULTS I: ASSAY
Table 1 (a) – Assay Results for CLA Tablets
Table 1 (b) – Assay Results for CLA Suspensions
13
Sample Code
C1 C2 C3 C4 C5 C6 C7
% Content 100.9 100.2 100.1 102.1 98.8 99.3 98.7
C8 C9 C10 C11 C12 C17
101.5 102.0 98.8 98.4 105.9 103.5
Sample Code
C13 C14 C15 C16 C18
% Content 107.8 108.8 99.5 109.6 110.1
RESULTS II: ACIDIC DEGRADATION
CLA std incubation - 37 oC in 0.1 M H3PO4 (pH 1.4) and 0.1 M HCl (pH 1.2)
Table 2 – Acid Degradation Parameters for CLA Std
14
Degradation Parameters
pH 1.4 pH 1.2
Half life (min) 185 36.7
Rate constant (min-1) 3.7 x 10-3 19 x 10-3
% API degradation in 40 min
13.8 60
RESULTS III: DISSOLUTION AT PH 1.2
Fig. 2 – Chrm for dissolution at pH 1.2, 30 min.
Dissolution proceeded with concurrent degradation – profiles created using Total Clarithromycins
0.0 5.0 10.0 15.0 20.0 min
-25
0
25
50
75
100
125
150
mAU 205nm,4nm (1.00)
DECL
CLA
15
RESULTS VI: F2 FACTORS AT PH 6.8
Fig. 5 – Similarity factors at pH 6.8
Compliance rate 50% (6/12) 18
F2 FACTORS – COMPLIANT SAMPLES
Table 3: Similarity factors for compliant samples
Overall compliance rate 25% (4/16 products)19
Sample Code
Dosage Form
f2 factors (%)
pH 1.2 pH 4.5 pH 6.8
C1 Tablet 80.4 93.6 54.8
C6 Tablet 54.6 52.4 64.4
C11 Tablet 64.7 80.9 61.8
C17 Tablet 72.2 75.2 55.2
F2 FACTORS – NON-COMPLIANT SAMPLES
Table 4: Similarity factors for non-compliant samples
20
Sample Code
Dosage Form
f2 Factors (%)
pH 1.2 pH 4.5 pH 6.8
C2 Tablet 46.0 30.0 54.8
C3 Tablet 40.2 53.7 35.5
C4 Capsule 69.2 16.9 26.5
C5 Tablet 28.8 61.5 33.3
C7 Tablet 37.9 25.3 27.6
C8 Tablet 58.9 69.5 45.4
C9 Tablet 44.8 34.2 34.7
C10 Tablet 22.2 56.6 79.7
C13 Susp. ND ND 42.4
C14 Susp. ND ND 14.3
C15 Susp. ND ND 15.2
C18 Susp. ND ND 42.0
DISCUSSION
Variability in product performance
Table 5 – Inconsistent Products
Gastric pH 0.5 - 2 adults, 1.5 - 3 children, 2 sick state
Gastric residence time 0.5 – 2 hrs Significant degradation noted at 30 min, pH 1.2
Product Code
f2 factors (%)
pH 1.2 pH 4.5 pH 6.8
C2 46.0 30.0 55.8
C8 58.9 69.5 45.4
C10 22.2 56.6 79.7
21
DISCUSSION (CONT’D) Variability in performance of innovator products
in different markets:
Significant differences not expected due to change in site – GMP, SUPAC-related guidelines
Minimal API release for suspensions C14 and C15 – implications of sub-optimal product dissolution
22
pH 1.2 4.5 6.8
f2 Value (Tabs) 72 75 55
f2 Value (Susp.) ND ND 42
CONCLUSION
Not all available CLA products meet quality standards
Proof of quality and pharmaceutical equivalence requires more than assay and single point dissolution tests
Role of DRAs critical in QA of pharmaceuticals
Pre-registration
Pharmacovigilance - effective, sustained, targeted
Staff – proper education, training, experience23
RECOMMENDATION
In vitro dissolution profiling to be included in routine QC and post-marketing surveillance tests
Sustained PMS and PV activities by DRAs
Sufficiently deterrent measures for non-compliant products by DRAs to discourage circulation of poor quality products
Further studies on other antibiotics in circulation, special attention paid to macrolides 24
ACKNOWLEDGEMENTS
Supervisors - Dr. K. O. Abuga
- Dr. H. K. Chepkwony
NQCL management and staff
University of Nairobi
Ministry of Health
Technical staff – C. Rotich, D. Nyamweya, J.
Kalama, H. Mugo, O. King’ondu, J. Nguyo 25