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Advances in Urinary Catheter Technology
Introduction
stances adhere to the surface of the catheter.3 It The first recorded use of a urethral catheter was has been the focus of considerable study.
in ancient Egypt, when papyrus reeds were Encrustation may happen whether the urine used to artificially drain the bladder.
present is infected or sterile, and is thought to Subsequently, a variety of other materials, involve a number of steps, commencing with including metals (bronze, copper, silver and the adsorption of urinary proteins onto the sur- tin), and animal skins were used to produce face of the catheter, with subsequent formation primitive catheters. The first rubber catheters of a biofilm to which other materials, eg. bac- were produced in the 1800s, initially without, teria, may adhere. A significant proportion of and later with, the provision of a balloon to aid the studies with respect to encrustation and in retaining the catheter in the bladder. Today, biofilm formation have been performed with Robyn J S Webber, MD
urinary catheters can be made from a number of ureteric stents, but some of their findings may FRCSEd(Urol),
materials, including latex, PVC and silicone.
also be applied to the development and use of is a Consultant Urologist atHairmyres Hospital in East They are specifically designed for different long-term urinary catheters. It has been sug- uses; short and long-term indwelling catheters, gested that the actual protein content of and for intermittent self-catheterisation.
nonencrusted stents;4 a finding that could well disease. Her other interestsinclude the management of associated with urinary catheter use. These be extrapolated to urinary catheters, and may include discomfort and trauma on insertion, be of practical use in the search to find ways of and the risks of urinary tract infection and reducing or entirely preventing encrustation catheter encrustation. Clearly, the degree of rel- from occurring. Once biofilm formation has evance of each of these issues varies with the commenced, the process currently is not able to situation in which the catheter is being used, be reversed, and if bacteria are present, and but in all cases there has been considerable adherent to the catheter, the biofilm may pro- research into developing catheter technologies tect the organism from the effect of antibiotic to combat each specific potential complication.
agents.5 Encrustation may also occur in sterile This article summarises some of the difficulties urine, and frequently these encrustations con- encountered in the past, and examines some of sist of calcium oxalate crystals. This process is the emerging technologies for dealing with less well understood than encrustation in the presence of infection. In an attempt to avoidthe development of encrustation, various mea- Biocompatibility
sures have been tried, including the use of Modern urinary tract catheters are largely well long-acting antimicrobial coatings, and treat- tolerated, and this may almost be taken for ments designed to detach biofilms as they granted. However, this was not always the case.
form. Currently however, these measures are far Whilst, not surprisingly, early catheters may from perfected, and encrustation will remain a not have been particularly comfortable or com- significant problem for indwelling catheters for patible with human tissues, biocompatability has really only been addressed in recent years. Itwas during the 1980s that it was first recog- Issues in intermittent self-
nised that biocompatibility was an important catheterisation
issue to consider, and at that time many cases of catheterisation (ISC) as having a vital role in catheterisation with a latex catheter were the management of a variety of bladder disor- reported. Interestingly, the cause in most ders, has brought its own unique set of practi- instances was not actually latex, but a reaction cal problems. Clearly encrustation is not an to substances added to the latex at the time the issue, but as with longer-term catheters, those catheter was manufactured.1 Following this dis- for intermittent use must be inert and comfort- covery, the testing of new urinary catheters for able for the patient, as well as being safe, easy biocompatibility assumed a new importance, to use, and with minimal risk of promoting and is now mandatory. A variety of tests may be infection. Previously PVC catheters (with an performed to assess biocompatibility, including additional lubricating agent) were used for in vivo animal studies, and experiments involv- ISC, and are still used by some patients. A ing the exposure of proposed new catheter number of complications have been recognised materials to cultures of human urothelial cells.2 associated with their use, including an allergyto the lubricant, and the development of ure- Biofilms and encrustation
thral strictures and false passages in men; the For indwelling catheters, be they urethral or suprapubic, encrustation may prove a signifi- cant problem. Encrustation is a complex pro- The introduction of single use, hydrophilic cess, in which crystalloid and colloid sub- coated catheters for ISC has meant that PVC Correspondence address:
Mrs Robyn J S Webber,
Consultant Urologist,
Hairmyres Hospital,
East Kilbride,
The first rubber catheters were produced in the 1800s,
“initially without, and later with, the provision of a balloon
to aid in retaining the catheter in the bladder
LEVITRA 5mg / 10mg / 20mg film-coated tablets.
(Refer to SmPC before prescribing.)
Presentation: Each tablet contains 5mg / 10mg /
20mg vardenafil (as hydrochloride trihydrate).
Indications: Treatment of erectile dysfunction. To
catheters for intermittent use must be inert and
be effective, sexual stimulation is required. Not for
use by women. Dosage: Adult men: 10mg
comfortable for the patient, as well as being safe, easy to use,
approximately 25 to 60 minutes before sexualactivity. Based on efficacy and tolerability the dose and with minimal risk of promoting infection ”
may be increased to 20mg or decreased to 5mg.
The maximum recommended dose is 20mg onceper day. Can be taken with or without food, onsetof activity may be delayed if taken with a high fatmeal. Elderly men: A first dose of 5mg should beused. Mild and moderate hepatic impairment,severe renal impairment: A starting dose of 5mg catheters have been largely (but not entirely) Products Inc); a hydrophilic coating, which can should be considered. With other medicinal superceded. These catheters are supplied with a be used alone, or can be linked with an antimi- products: In combination with erythromycin, the coating, which, when wetted prior to insertion crobial coating. The antimicrobial coating is dose of vardenafil should not exceed 5mg.
Children and adolescents: Not indicated.
in the urethra has a low coefficient of friction designed to gradually release antimicrobial Contraindications: Coadministration with nitrates
(ie. is very slippery), making such catheters agents when in contact with bodily fluids. This or nitric oxide donors in any form; men for whom easier and more comfortable for patients to can be customised, so that the rate at which sexual activity is inadvisable (e.g. severe insert. Studies have suggested that with the use these agents are released can be varied, so there cardiovascular disorders); severe hepatic impair-ment; endstage renal disease requiring can be an initial release, followed by a slower, dialysis; hypotension; recent stroke or myocardial catheters, the incidence of urethral strictures more controlled release of the antimicrobial infarction; unstable angina; known hereditary and false passages is reduced.6 These catheters agent. The ability to vary this rate means that retinal degenerative disorders; concomitant use ofpotent CYP3A4 inhibitors (ritonavir, indinavir, the antimicrobial properties may be altered, ketoconazole and itraconazole (oral form)) in hydrophilic coating (and therefore the degree depending on whether the catheter is for long- men older than 75 years; hypersensitivity to var- of lubricity) wears away with repeated use. In term or intermittent use. As catheters with denafil or to any of the excipients. Warnings
and Precautions: Medical history and physical
addition, it has been shown that these catheters these coatings become more freely available, it examination should be undertaken to diagnose should not be left inserted in the urethra for will be interesting to see not only whether rates erectile dysfunction and determine potential prolonged periods (particularly in men), as of catheter associated infection are reduced, but underlying causes. Consider cardiovascular status, they can become sticky. In this situation, force also, for long-term catheters, where there may since there is a degree of cardiac risk associatedwith sexual activity. Vardenafil has vasodilator may be required to remove the catheter from be any reduction in the rate of encrustation.
properties, resulting in mild and transient decreases in blood pressure. Use with caution in patients with anatomical deformation of the penis Coatings for urinary catheters
or conditions which predispose to priapism (such The development of catheters for the urinary as sickle cell anaemia, multiple myeloma or It is vital to ensure the smooth passage of any tract has become a highly technical exercise, leukaemia). Combination with other treatments urinary catheter, and this is especially impor- with the aim of producing catheters that are for erectile dysfunction is not recommended.
tant with those catheters used for ISC. Again it easy to use for patient and health professional Concomitant use with alpha-blockers is not recommended. Concomitant use with potent is important to reduce the risk of infection alike, with a low associated rate of infection, CYP3A4 inhibitors (ritonavir, indinavir, associated with catheter use to a minimum.
itraconazole and ketoconazole (oral form)) should Hence, there has been interest in the develop- encrustation remains the greatest problem yet be avoided. Dose adjustment might be necessaryif erythromycin is given concomitantly. Avoid ment of antimicrobial coatings for use with to be solved satisfactorily. In general though, grapefruit juice. Administration to patients with bleeding disorders or active peptic ulceration only catheters. An ideal situation may be to have a hydrophilic and antimicrobial coatings have after careful benefit-risk-assessment. Vardenafil combined hydrophilic and antimicrobial coat- meant that catheterisation, especially for those has not been studied in patients with spinal cordinjury or other CNS disease, hypoactive sexual ing, and such agents are now under develop- patients practising ISC is, with appropriate desire and in patients who have undergone pelvic ment. One such a coating is LubriLAST™ (AST surgery (except nerve-sparing prostatectomy),
pelvic trauma or radiotherapy. Undesirable
Effects: Flushing, headache, dyspepsia, nausea,
dizziness, rhinitis, hypertension, photosensitivity
reaction, abnormal vision, hypertonia,
hypotension, syncope and erectile disturbance.
Two cases of priapism have been observed in a
Acknowledgement
Phase I clinical study with twice the maximum recommended dose of vardenafil. Serious I would like to acknowledge the assistance of Dr Min-Shyan Sheu; Director of
cardiovascular events, including cerebrovascularhaemorrhage, myocardial infarction, sudden Research and Development at AST Products Inc (www.astp.com), who kindly
cardiac death, transient ischaemic attack and ven-tricular arrhythmia reported post marketing in provided advice on the use of hydrophilic and antimicrobial catheter coatings.
temporal association with another medicinal
product in this class. Legal Category:
POM. Marketing Authorisation Numbers:
EU/1/03/248/001-012. Marketing Authorisation
Holder: Bayer AG, D-51368 Leverkusen, Germany.
Package Quantities and Costs: Packs of 4, 5mg
tablets £16.59; Packs of 8, 5mg tablets £33.19;
Packs of 4, 10mg tablets £19.34; Packs of 8, 10mg
References
tablets £38.67; Packs of 4, 20mg tablets £23.50;
Packs of 8, 20mg tablets £46.99. Further
1. Ruutu ML, Talja MT, Andersson LC, Alfthan OS.
information available from:
Biocompatibility of urinary catheters – present status. Encrustation of biomaterials in the urinary tract. Pharmaceutical Division, Bayer House, Strawberry Scand J Urol and Nephrol 1991;138:235-8.
Hill, Newbury, Berkshire RG14 1JA, United Kingdom, Telephone: (01635) 563000. Version:
2. Pariente JL, Bordenave L, Bareille R et al. First use of 001. Date of preparation: February 2003.
cultured human urothelial cells for biocompatibility 6. Waller L, Jonsson O, Norlen L, Sullivan L. assessment: application to urinary catheters. Clean intermittent catheterization in spinal cord injury 1. Potempa A-J et al. Poster presented patients: long-term follow-up of a hydrophilic low friction V Congress ESSIR, Hamburg December 2002.
3. Choong SKS, Whitfield HN. Urinary encrustation of technique. J Urol 1995;153(2):345-8.
2. Valiquette L et al. Poster presented 10th alloplastic materials. J Endourol 2000;1:19-23.
7. Vaidyanathan S, Krishnan KR, Soni BM, Fraser MH.
4. Santain M, Motta A, Denyer SP, Cannas M. Effect of urine Unusual complications of intermittent self- conditioning film on ureteral stent encrustation andcharacterization of its protein composition. catheterisation in spinal cord injury patients.

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