Capturing The Significance of X-Ray Crystallography in Pharmaceutical Field:
The Application to Characterize New Salt, Co-Crystal and Co-Amorphous
Etsuo Yonemochi
Department of Physical Chemistry, School of Pharmacy and Pharmaceutical Sciences, This document was presented at PPXRD - Pharmaceutical Powder X-ray Diffraction Symposium Sponsored by The International Centre for Diffraction Data
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PPXRD Website – www.icdd.com/ppxrd ICDD Website - www.icdd.com Acyclovir
• Guanosine analogue antiviral drugs. • The treatment of herpes simplex virus infections.
2 Outline Screening and Characterization Screenig methods and used additives Selected cocrystals (PXRD、TG/DTA、DSC） Application for oral dosage form Intrinsic dissolution of selected cocrystal Crystal structure of selected cocrystal Mechanism for solubility enhansment Application for transdermal dosage form Transdermal adsorption propertiy of selected complex Solubility of amorphous comples Improvement of transdermal properties 2/3 Hydrate
Commercially available Recrystalized from ethanol solution
P21/n a 25.459(1)Å b 11.282(1)Å c 10.768(1)Å β 95.16(1)° Volume Column structure 3080.342Å3 Stacking purine moiety Z 12 R-factor 5.3％ Dihydrate From ammonium solution
P-1 a 6.8386(7)Å b 11.3679(14)Å c 14.942(2)Å α 82.845(4)° β 82.419(3)° γ 89.326(3)° Channel structure Volume 1142.5(2)Å3 Stacking purine moiety Z 4 R-factor 7.71％ Anhydrate2 Dehydration of hydrates
P21/c a 10.9399(6)Å b 11.1837(6)Å c 8.1164(4)Å Stacking purine β 108.6277(34)° Volume moiety 941.009Å3 Z 4 Anhydrate2
Crystallization by Vapor-Diffusion. Procedure. (DMF+Acetonitrile)
P 212121 a 4.5387(10)Å b 15.0308(3)Å c 28.3320(6)Å Volume 1932.82Å3 Z 8 R-factor 9.88％ Different stacking mode Dissolution properties for acyclovir polymorphs
Intrinsic dissolution rate 1.5 ・area for disson：0.2 cm2） Similar dissolutin rate ・pH 6.8 Phosphate buffer 1.2 ・37℃
. ・50 rpm anhydrate1 c n
o 2/3hydrate ) 0.9 C L r i m / v g o l μ c ( 0.6 Anhydrate2 y c 2hydrate A
0.3
polymorphs 0 0 1 2 3 4 5 Time (min) Transformation of anhydrate to hydrate was quick. Anhydrates were useless Hydration mechanisum？ Hydration properties for acyclovir anhydrate2
Reversible
Anhydrate 2 Dihydrate 2/3 hydrate Hydration properties for acyclovir anhydrate1
25℃ RH95％ 1week
Anhydrate 1 2/3 hydrate Dihydrate Irreversible Anhydrate 2 Comparison between transition behavior and stacking mode antiparallel parallel parallel
2/3 Hydrate Anhyd. 1
Anhyd. 2 Di hydrate
antiparallel antiparallel Similarity of stacking The phase transition mechanism is complicated. X-ray DSC
Anhydrate Form 2
Anhydrate Form 4
Anhydrate Form 2
Anhydrate Form 4
Anhydrate Form 3
2/3 hydrate
12 XRPD patterns of acyclovir using HT capillary sample holder
2.5e+004
2.0e+004 Intensity(cps)
1.5e+004 Anhydrate Form 2 (RT)
1.0e+004 Anhydrate Form 4 (210℃)
5.0e+003 2/3 hydrate (RT) 20 40 60 80 2-theta (deg) 13 Comparison from the view of stacking structure
antiparallel
2/3 hydrate Anhydrate Form 4 Anhydrate Form 2
antiparallel
parallel
parallel
14 Anhydrate Form 1 Phase Transition of Acyclovir polymorphs
Anhydrate 3
120oC
o RH95% 170 C 2/3 hydrate Anhydrate 1 at 25oC
Anhydrate 4
RH0% RH20% o at 25oC 170 C at 25oC
Dihydrate Anhydrate 2 Conclusion • There are two packing manners for purine moiety. Anhydrate 1, anhydrate 2, 2/3 hydrate and ACV dihydrate were packed in parallel, antiparallel, mixture of parallel—anti-parallel and parallel manners, respectively.
• Based on the packing manner of ACV, it can be seen why the phase transformation occurs with readily or with difficulty.
16 Outline Characterization Screenig methods and used additives Selected cocrystals (PXRD、TG/DTA、DSC） Application for oral dosage form Intrinsic dissolution of selected cocrystal Crystal structure of selected cocrystal Mechanism for solubility enhansment Application for transdermal dosage form Transdermal adsorption propertiy of selected complex Solubility of amorphous comples Improvement of transdermal properties dissolution properties
O N HN N Sprangly soluble in water O H2N N OH
Dissolution rate and solubility for water Activity related to the solubility in base Oral dosage form Transdermal Bioavailability：low Transdermal Absorption ：low
D. Patel, et al. Drug. Dev. Ind. Pharm. 33:1318 (2007). D. J. Freeman, et al. Antimicrob. Agents Chemother. 29:730 (1986). Improvement of solubility Improvement of the physicoshemical properties
methods
polymorphs Salt formation Package gringing Solvate Cocrystal Solid dispersion amorphous
O N HN N O H2N N OH Applicaton for oral dosage form Cocrystal→Improvement of dissolution properties Application for transdermal dosage form Amorphization→Increase the solubility in base→ Increase the absorption Cocrystal・・・
polymorph hydrate/solvate pure API salt of API of pure API of API
・単位格子中に固体分子 種以上含有 Multicomponent crystal2 Neutral API ・水素結合等で分子が結合 ・多Hydrogen成分結晶 bonding, Neutral Water/solvent
Charged API 単Multicomponent一分子から構成される crystal結晶では得られない Counter ion pharmaceutical に期待 Hydrogen物性・機 bonding,能の発 Neutral現 Cocrystal former cocrystals ACV has many functional groups, O N Capable to make hydrogen bonding HN N O Cocrystal formation H2N N OH Generally recognized as safe compound :Hydrogen bond donor or acceptor sites Amorphization of Acyclovir
Melt
O Decomposion N HN Solvent evaporation N O Unstable H2N N OH Spray dry Addition of polymer Freeze dry
High Cost Decrease the diffusion rate in base
Comventional methods isn’t suitable for the amorphization
Preparation of Amorphous complex with additives Outline Characterization Screenig methods and used additives Selected cocrystals (PXRD、TG/DTA、DSC） Application for oral dosage form Intrinsic dissolution of selected cocrystal Crystal structure of selected cocrystal Mechanism for solubility enhansment Application for transdermal dosage form Transdermal adsorption propertiy of selected complex Solubility of amorphous comples Improvement of transdermal properties Screening methods
Acyclovir anhydrous Excipient Screening by form 2 Solvent, Grinding
Solvent method Grinding method
Solvent Liquid assisted grinding Neat grinding (Solvent drop method) Hot suspension of drug and cocrystal former Liquid assisted grindig
Filtration Solvent Ground manually at room temperature Ground manually at room temperature Saturated solution of 14additives drug and cocrystal former
Slow evaporation 9 solvent or Cooling
Crystallized complex or Amorphous complex Evaluated by PXRD, Themal Analysis PXRD, TG/DTA Generally recognized as safe compounds used
O OH OH O O OH O O O HO OH O OH HO H N OH HO OH O 2 OH O OH OH NH2 Citric acid Tartaric acid Malic acid Glycine Alanine
O NH O O HO OH H N N OH 2 H OH O NH2 NH2 Stearic acid Aspartic acid Arginine
O
OH O O O Palmitic acid NH NH2 H N NH S 2 2 O O N O OH Urea Nicotinamide Saccharin Docosanoic acid
O
OH Lauric acid Existence of the records as Oral or Trandermal application PXRD patterns of samples
Anhydrate1
5 10 15 20 25 Anhydrate2
5 10 15 20 25 2/3 hydrate
5 10 15 20 25 2hydrate
Relative intensityRelative 5 10 15 20 25 Citric acid
5 10 15 20 25 Cocrystal
5 10 15 Halo2 0pattern 25 Amorphous complex 5 10 15 20 25 2θ/ degree TG/DTA curve of samples
0 0 169℃ Citric acid Anydrate1 Weight loss DTA curve 100 100
0 exo.→ 0
25 80 135 190 245 300 T 25 80 135 190 245 300
Δ
Weight loss (%) loss Weight
Anhydrate2 157℃ Cocrystal
100 100
→ exo.→ 0 25 80 135 190 245 300
T 25 80 135 190 245 300
Δ
Weight loss (%) loss Weight 2/3hydrate
100 0 25 80 135 190 245 300 Clear difference in curves
2hydrate No possibility of the 250℃ formation of solvate 100
25 80 135 190 245 300 DSCcurves of amorphous complex
Tg ) mW
40 50 60 70 80 90
Tg Heat flow(
↑ Endo 68℃
-40 -20 0 20 40 60 80 100
Temperature (ºC)
Glass transition temperature Tg was higher than the room temperature. Confirmation of the physical stability of amorphous complex Outline Characterization Screenig methods and used additives Selected cocrystals (PXRD、TG/DTA、DSC） Application for oral dosage form Intrinsic dissolution of selected cocrystal Crystal structure of selected cocrystal Mechanism for solubility enhansment Application for transdermal dosage form Transdermal adsorption propertiy of selected complex Solubility of amorphous comples Improvement of transdermal properties Crystal structure of Acyclovir‐Citric acid Cocrystal
Single crystals weren’t obtained
Crystal structure analysis using powder diffraction data obtained by synchrotron radiation
Stoichiometry of Acyclovir : Citric acid was 1:1 Comparison of stacking structure of Acyclovir and its cocrystal Anhydrare2 Acv-Citric acid Cocrystal
Cocrystal
Stacking structure of Purine frame Citric acid
Un-stabilize the stacking structure by intercalation of citric acid
Enhancement of the solubility Distance in the purine frame in the crystals
14
) Å 12
10 8 No difference 6
4
stacking distance stacking( distance
π π - 2
π 0 Anhyd.1 Anhyd.2 2/3hydrate Dihydrate Cocrystal
Change in the crystal strucuture by cocrystal Improvement of dissolution property Saturated Solubility of Cocrystal in various solvents
10.00 Enhancement of solubilty : Distilled water 8.00 : Phosphate buffer pH 6.8
: Ethanol 6.00
4.00
2.00 Saturated solubility (mg/mL)
0.00 1 2 3 4 5 6 7 8 9 Acyclovir anhydrous form 2 ACV-TA-PM ACV-TA cocrystal
Physical mixture showed the similar solubility compare to the Cocrystal ACV and Citric acid was interacted, even in the solution. Initial dissolusion profiles for ACV samples
5
● ACV-TA cocrystal ◆ Acyclovir anhydrous form 1 Cocrystal 4 ▲ Acyclovir two-thirds hydrate ■ Acyclovir anhydrous form 2 × Acyclovir dihydrate ○ ACV-TA-PM 3 (μg/mL) 2 Polymorphs, PM Acyclovir concentration
1
0 0 1 2 3 4 5 Time (min)
Remarkable enhancement of solubility was observed. Mechanism for improvement of dissolution property of ACV by Cocrystal formation
water
Cocrystal
Expansion of Purine layer water
Decrease in the lattice energy Outline Characterization Screenig methods and used additives Selected cocrystals (PXRD、TG/DTA、DSC） Application for oral dosage form Intrinsic dissolution of selected cocrystal Crystal structure of selected cocrystal Mechanism for solubility enhansment Application for transdermal dosage form Transdermal adsorption propertiy of selected complex Solubility of amorphous comples Improvement of transdermal properties In vitroTransdermal test for ACV ointment
＜Franz type diffusion cell＞
15 mm Threaded cell top sample （Dosagearea : donor1.77 areacm2）
HairlessMembrane mouse back skin Cell ring water（37℃） pHReceptor 6.8 phousphate solution buffer
Sampling port
Helix mixer 9 mm Cell 15 mm×7 mL
Replace port with bubble trap Magnetic stirrer Water jacket Ointment base：Macrogol Permeability of ACV
・Low permeaability of ACV 0.20 d e t ・22hours were necessary to permeate a e m r 0.15 e p
) t )
2 n 2 u m o c / 0.10 m g a μ
μg/cm ( e
( v i t a
l 0.05 u m u C 0.00
Cumulativeamountpermeated 0 5 10 15 20 25 30 Time (hr)
Application of amorphous complex？ Solubility of ACV in PEG400
Saturated solubility of ACV in Mcrogol base PEG400：Liquid 1.00 Macrogol base
0.80 PEG4000：Solid
0.60 Increased
(mg/mL) 0.40
0.20 Saturatedsolubility in 400PEG
0.00 Acyclovir (crystalline) ACV-CA-PM ACV-CA amorphous Microscopic picuture of samples
ACV‐Tartalic acid ACV‐Tartalic acid ACV Physical Mix. amorphous (a) (b) (c)
25 µm 25 µm 25 µm
Low solubility Low solubility Solubility：High ↓ ↓ ↓ Crystallization Crystallization Almost dissolved Amorphous ACV complex was dissolved in super saturated states. Permeability of ACV samples
60 ● ACV-CA amorphous ◆ Acyclovir (crystalline) d 50 ○ ACV-CA-PM e t a e m r 40 e p t ) 2 n u m ) 2 o c
/ 30
m 1 g a μ
( e
v 0.5 i t 20 a l
u 0 Cumulativeamount permeated (μg/cm m 0 10 20 30 u
C 10 Time (hr)
0 0 5 10 15 20 25 30 Time (hr) Improvement of permeability of ACV was achieved Advantage of amorphization for transdermal application Comventional amorphization
Enhan drug drugdrugdrugdrugdrug cer MN EP dermis dermis
Chemical, physical Increase the concentration enhacement methods might gradient may not affect the affects the barrier function of barrier function skin
Safer method for transdermal application