Water infusion and drug effusion in drug release polymers and drug diffusion in mucosae and muscle

1. Water infusion and drug effusion in drug release polymers and drug diffusion in mucosae and muscle A S Clough, F E Gauntlett, M S Rihawy University of Surrey M Braden, M P Patel, QMW, London J Booth, Astra- Zeneca, Macclesfield A Cruchley, Royal London and St Barts Hospital University of Surrey Guildford Surrey England

2. Outline of Talk • ION BEAM MICRO-ANALYSIS OF DIFFUSION • WATER INGRESS INTO AND DRUG EGRESS FROM IN-MOUTH POLYMERS • WATER INGRESS INTO AND DRUG EGRESS FROM CYLINDRICAL IN-BODY POLYMERS • DRUG INGRESS INTO ORAL MUCOSAE • DRUG DIFFUSION IN MUSCLE • FUTURE WORK.

3. Ion Beam Analysis at Surrey 2 Years ago Accelerator: 2MV Van de Graaff Ion source: 3He Scanning Micro-beam : Beam size 10m to 200m Beam current - nA to A Beam scan of up to 3mm  3mm. Magnet V de G Object aperture Quadrupole focussing magnets Computer controlled raster scanned deflection plates Scanning microbeam target chamber LN2 cooled sample stage

4. Scanning Microbeam Target Chamber Side view Front view of sample stage Particle detectors Cu blocks X-ray detector Sample Scanning zone Focussed 3He scanning microbeam LN2 cooled sample stage

5. NRA (Nuclear Reaction Analysis) • Protons detected from the reaction: • 3He + d  p +  Q = 18.4 MeV • Rutherford BackScattering (RBS) • PIXE (Particle Induced X-ray Emission)

6. Water and drug profiles following water ingress into in-mouth planar polymers • Water uptake and drug release have been characterised for: • chlorhexidine diacetate drug loadings of 0%,4.5%,9% and 15% of dry weight polymer • 3 polymers – Addition Cured silicone, Condensation Cured silicone and PEM/THFM • 2 immersion solutions – 90% pure H2O/10%D2O and 90% PBS/10%D2O • a series of 7 immersion times from 1 hour to 6 months • using three techniques: • scanning 3He ion microbeam NRA ,PIXE and backscattering to profile the water ingress, correlate water and drug distributions and enable inter-sample normalisation • gravimetric measurements to establish absolute normalisation of water uptake • UV measurements to establish mass of drug released to immersion solution.

7. Sample Preparation • Mix drug and silicone polymer, press into oblongs 20 mm  10 mm  ~1 mm. • Immerse in 50 ml water (10% D2O/ 90%H2O) or buffer solution (10% D2O/ 90% Buffer solution) at 37C • Remove, hold between copper blocks on sample plate, cut section at the block height; plunge in LN2 • Mount sample plate on LN2 cooled sample stage and do 3He beam scan

8. NRA Spectrum Ln counts RBS Protons Alphas Channel Number Drug-containing silicone polymer exposed to 90%H2O/10% D2O at 37C

9. Cu Al Si Cl Example of an addition-cured polymer PIXE spectrum, drug loading 4.5%, PBS immersion time 1 hour, displayed using a square vertical scale.

10. 9% Drug loaded Addition Polymers, 2w exposure to PBS at 37 C RBS Silicon X-rays Cl X-rays Protons from Deuterium

11. 1-d Diffusion Profiles of Water from 90%H2O/10%D2O Addition cured Polymer Condensation Cured Polymer PEMA/THFM

12. 1-d water diffusion profiles from 90%PBS/10%D2O Addition Cured Polymer Condensation Cured Polymer PEMA/THFM

14. Drug Release and Water Uptake from 90%H2O/10%D2O at 37C Addition Cured Silicone Condensation Cured Silicone PEMA/THFM

15. Drug Release and Water uptake from 90% PBS/10%D2O at 37C Addition Cured Condensation Cured PEMA/THFM

17. Cylindrical Polymer/Drug Depots • Solid cylindrical depots (2.25 mm in diameter) of poly(dl-lactide) P(DL)LA loaded with goserelin in ratios of 20%, 30% and 40% by weight respectively were prepared by melt extrusion of drug/polymer mixtures. • Many sections 18 mm long were cut, weighed and immersed in separate glass jars containing 45ml buffer solution mixed with 5ml D2O. These were held at a constant temperature of 37C for times between 1 hr and 7 days. • On removal they were dried lightly with filter paper, weighed and cut into sections 3mm long. These were transferred to the sample plate, held at liquid nitrogen temperature and subsequently scanned with the 3He ion microbeam – energy 1.3 MeV, diameter 10 microns, current ~ 1nA.

18. Cylindrical Polymers – colour scale normalised to 7 day 30% data 1 Day 4 Days 7 Days 1 Hour 4 Hours 20% 30% 40%

19. Water diffusion into 40% drug loaded cylindrical drug-release polymer from 90% PBS/ 10% D2O at 37C – colour scale normalised to 1d data 1hr 4hr 1d 4d 7d

20. Water Uptake of Drug Depots for Different Immersion Times

21. Fractional Weight increase of Polymer after immersion

22. Fraction of Drug Released

23. Ion Beam Analysis at Surrey Today Present Accelerator: 2MV Tandetron Ion source: 3He, 4He or protons Scanning Microbeam : Beam size 1m to 200m Beam current - nA to A Beam scan of up to 2.5mm  2.5mm. Nano beam (~10 nm spot size) under construction External Scanning microbeam (~ 10 microns spot size) Tandetron Object aperture Magnet Magnet Quadrupole focussing magnets Computer controlled raster scanner deflection plates Scanning microbeam target chamber LN2 cooled sample stage

24. Drug diffusion in pig mucosa Mucosa exposed to 10% solution of chlorhexidine sulphate in water for 90 minutes Cut perpendicular to surface, backcooled with LN2, and scanned by 2 MeV, 2 micron spot size, proton microbeam. Characteristic X-rays detected.

25. FlowThrough Chamber Cover slip prevents Reservoir of test compound evaporation of test compound. Threaded collar allows tightening of Teflon chamber chamber without disturbing tissue Inlet port Tissue Outlet port Viewing port allows air bubbles to be checked for.

26. Cross-section of mucosal epithelium

29. Fluorinated Drug Diffusion in porcine muscle tissue Problem: Detecting fluorine at pp104 with microbeam currents (100pA) and spatial resolution of 1 micron Solution: Use 3.2 MeV ions and the reaction : 19F (p, ) 16O* Characteristic 6.05 MeV -rays detected with high efficiency hyper-pure Germanium detector

30. Spectrum of  -rays from 19F (p, ) 16O* N  -Energy (MeV)

32. Work in progress • Diffusion of drugs that contain either fluorine or chlorine or are deuterated into different biological tissues • Diffusion of water(labelled with deuterium) at low concentration into resins and polymer films • Diffusion of chlorine and water into cements, mortars and concrete • Development of nano-beam and associated detectors

33. WHERE?

34. Reactions Detected: (iii) p + 11B   + 8BeQ=8.582 MeV RBS  Sensitivity Estimate : parts per 105 Spatial Resolution of Microbeam : ~ 1m

35. Reactions Detected: (ii) p + 19F   + 16OQ=8.114 MeV RBS RBS Pile-up  Sensitivity Estimate : parts per 104 Spatial Resolution of Microbeam : ~ 1m

36. The CdZnTe Array • Connected in 3 groups of 4 detectors • Outputs are summed together

37. Reactions Detected: (i) 3He + D   + pQ=18.352 MeV  p Sensitivity Estimate : parts per 104 Spatial Resolution of Microbeam : ~ 1m

38. The CdZnTe Detectors • 15mm x 15mm x 3mm • can absorb the full energy of protons up to ~15MeV • pin connected to the front of the detector is earthed, via a thin (50-100nm) platinum contact layer diffused onto the crystal surface • other pin for signal

39. Cutaway View: ION BEAM Array Solid Angle The array is located ~1cm upstream of the target and subtends a useful solid angle of ~/2 steradians (1/8 sphere). (We are improving it to allow a solid angle coverage of  steradians).

42. 2-d maps showing diffusion of deuterated water into a planar glass sample - Scott 8330 exposed to 300 C D2O Cu RBS map Si X-ray map Deuterium map

43. X-ray spectrum Cu from Cu blocks Si from polymer matrix Drug –free polymer exposed to water at 37C

44. 3He backscatters

45. 1d profile: