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

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.

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

Side view Front view of sample stage Particle detectors LN 2 cooled sample stage Focussed 3 He scanning microbeam X-ray detector Scanning zone Cu blocks Sample Scanning Microbeam Target Chamber

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

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 H 2 O/10%D 2 O and 90% PBS/10%D 2 O a series of 7 immersion times from 1 hour to 6 months using three techniques:  scanning 3 He 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.

Sample Preparation Mix drug and silicone polymer, press into oblongs 20 mm  10 mm  ~1 mm. Immerse in 50 ml water (10% D 2 O/ 90%H 2 O) or buffer solution (10% D 2 O/ 90% Buffer solution) at 37C Remove, hold between copper blocks on sample plate, cut section at the block height; plunge in LN 2 Mount sample plate on LN 2 cooled sample stage and do 3 He beam scan

Ln counts Channel Number Protons Alphas RBS NRA Spectrum Drug-containing silicone polymer exposed to 90%H 2 O/10% D 2 O at 37C

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

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

1-d Diffusion Profiles of Water from 90%H 2 O/10%D 2 O Addition cured Polymer Condensation Cured Polymer PEMA/THFM

1-d water diffusion profiles from 90%PBS/10%D 2 O Addition Cured Polymer Condensation Cured Polymer PEMA/THFM

Addition Cured Silicone Condensation Cured Silicone PEMA/THFM Drug Release and Water Uptake from 90%H 2 O/10%D 2 O at 37C

Addition Cured Condensation Cured PEMA/THFM Drug Release and Water uptake from 90% PBS/10%D 2 O at 37C

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 D 2 O. 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 3 He ion microbeam – energy 1.3 MeV, diameter 10 microns, current ~ 1nA.

20%20% 30%30% 40%40% 1 Hour4 Hours 1 Day4 Days7 Days Cylindrical Polymers – colour scale normalised to 7 day 30% data

1hr 4hr 1d 4d 7d Water diffusion into 40% drug loaded cylindrical drug-release polymer from 90% PBS/ 10% D 2 O at 37C – colour scale normalised to 1d data

Water Uptake of Drug Depots for Different Immersion Times

Fractional Weight increase of Polymer after immersion

Fraction of Drug Released

Ion Beam Analysis at Surrey Today Present Accelerator: 2MV Tandetron Ion source: 3 He, 4 He 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. Magnet Computer controlled raster scanner deflection plates Quadrupole focussing magnets Tandetron Magnet Object aperture LN 2 cooled sample stage Scanning microbeam target chamber External Scanning microbeam (~ 10 microns spot size) Nano beam (~10 nm spot size) under construction

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.

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

Cross-section of mucosal epithelium

Fluorinated Drug Diffusion in porcine muscle tissue Problem: Detecting fluorine at pp10 4 with microbeam currents (100pA) and spatial resolution of 1 micron Solution: Use 3.2 MeV ions and the reaction : 19 F (p,  ) 16 O * Characteristic 6.05 MeV  -rays detected with high efficiency hyper- pure Germanium detector

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

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

Reactions Detected: (iii) p + 11 B   + 8 Be Q=8.582 MeV Sensitivity Estimate : parts per 10 5 Spatial Resolution of Microbeam : ~ 1  m RBS 

Reactions Detected: (ii) p + 19 F   + 16 O Q=8.114 MeV Sensitivity Estimate : parts per 10 4 Spatial Resolution of Microbeam : ~ 1  m RBS RBS Pile-up 

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

Reactions Detected: (i) 3 He + D   + p Q= MeV Sensitivity Estimate : parts per 10 4 Spatial Resolution of Microbeam : ~ 1  m  p

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

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). ION BEAM Cutaway View: Array Solid Angle

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

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

3He backscatters

1d profile:

S distribution after 90 min exposure to chlorhexidine sulphate solution P distribution after 90 min exposure to chlorhexidine sulphate solution

Cl distribution after 90 min exposure to chlorhexidine sulphate solution S distribution after 90 min exposure to chlorhexidine sulphate solution Direction of Chlorhexidine ingress