Salbutamol This poster presentation will show the pharmacodynamics and pharmacokinetics of Salbutamol. It will then explain the potential effects Salbutamol has on the body as well as showing how disease effects Salbutamol therapy. Funding and authorisation of Salbutamol will be described. The use of Salbutamol in my clinical practice will be discussed and recommendations will be made for colleagues around administration and monitoring of this drug. Salbutamol is a common drug for asthma relief Mann (2000). Therefore poster presentation focuses on the role of Salbutamol in the relief of Asthma.
Asthma Dunn et al. (2000) define Asthma as: •
Bronchial Smooth Muscle Constriction.
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Mucous Hyper-secretion (Mucus Plugs) in the Bronchi.
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Inflammation of Bronchial wall.
Figure 1: Bronchi during Asthma - Dr.Paul Communications Inc (2003)
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Pharmacokinetics Salbutamol is available for administration by the following routes: Inhalation, tablet, elixir, intravenous injection, subcutaneous injection, intramuscular injection.Spina et al. (1997) has completed animal testing on sub-lingual Salbutamol but it is not available in New Zealand. Absorption
Figure 2: Compiled from information gathered from the following sources - Pacific Pharmaceuticals Limited (2003), Apotex NZ Ltd (2003), Katzung (1998), GlaxoSmithKline NZ Limited (2003c), PHARMAC (2003), Galbraith et al. (1994)
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Distribution Salbutamol binds to and releases from plasma proteins as necessary.
Figure 3: Salbutamol binds to a plasma protein - Galbraith et al. (1994), Katzung (1998)
Metabolism Salbutamol absorbed in the gastrointestinal tract has a substantial first pass and is metabolised into Phenolic Sulfate.
Figure 4: Salbutamol Metabolism - GlaxoSmithKline NZ Limited (2003c)
Inhaled Salbutamol acts directly on smooth muscle of the upper airways bypassing metabolism in the liver. Excretion Salbutamol and Phenolic Sulfate are primarily excreted via the urinary system.
Figure 5: Excretion - Rang et al. (1999), Galbraith et al. (1994)
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Summary of Pharmacokinetics
Figure 6: Adapted from Adrenergic Agonist Effects - Galbraith et al. (1994), Rang et al. (1999)
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Pharmacodynamics
Figure 7: Pharmacodynamics of Salbutamol - Galbraith et al. (1994), Dunn et al. (2000)
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Salbutamol is a selective β2 agonist which primarily binds to β2 receptors at the synapse with very little binding to β1 receptors. Non selective medication, such as Adrenalin binds to β1 and β2 receptors. Salbutamol has an advantage in asthma treatment by minimising side effects associated β1 receptor stimulation which Adrenalin causes Mann (2000).
Figure 8: Direct Acting Agonist Action - Galbraith et al. (1994)
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Potential Drug Interactions
Figure 9: Drug interactions with Salbutamol - GlaxoSmithKline NZ Limited (2003c)
Contraindications / Warnings •
Hypersensitivity to ingredients of Salbutamol
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Chlorofluorocarbon propellants used in some aerosol inhalers can produce cardiac arrhythmias and sensitise the heart to adrenalin induced arrhythmias.
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Dunn et al. (2000) aerosol inhalers can affected by decreased temperature which increases particle size of drug making absorption more difficult.
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Salbutamol may cause fetal congenital abnormalities when used in pregnancy and its effects on a neonate when breast feeding are unknown.
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Effects of Salbutamol on Body Systems
Figure 10: Adverse Effects of Salbutamol - Compiled from information from Galbraith et al. (1994), Pacific Pharmaceuticals Limited (2003), MEDSAFE (2003), GlaxoSmithKline NZ Limited (2003a), Apotex NZ Ltd (2003), Douglas Pharmaceuticals Ltd (2003), GlaxoSmithKline NZ Limited (2003c,b), Katzung (1998)
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Effects of Disease on Salbutamol Therapy
Figure 11: Adapted from Galbraith et al. (1994), Douglas Pharmaceuticals Ltd (2003)
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Authorisation of Salbutamol
Figure 12: Classification of Medications - MEDSAFE (2003)
Salbutamol is a prescription medication and must be prescribed by a Medical Doctor. An exception according to GlaxoSmithKline NZ Limited (2003a) is Ventolin Elixir which is a Restricted or Pharmacist Only Medication.
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Funding Pharmaceutical Management Agency of New Zealand (PHARMAC) manage a Pharmaceutical Schedule on behalf of the Ministry of Health in New Zealand. This Schedule governs subsidisation to Pharmaceutical Manufacturers for that drug.
Figure 13: PHARMAC Structure and Role compiled using information from PHARMAC (2003)
New Zealand Pharmaceutical Manufacturers apply to have their drug listed on the Pharmaceutical Schedule. This decreases the cost of manufacture and in turn the cost of the drug to the public. 11
Pharmaceutical Schedule Listing for Salbutamol
Figure 14: Salbutamol on the Pharmaceutical Schedule from PHARMAC (2003).
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Clinical Practice Situation Drug Administration by Nurses
Figure 15: Compiled from information from -General Assembly of New Zealand in Parliament (1981), Burgess (1996).
An aid to correct administration of Salbutamol suggested by Galbraith et al. (1994) is the 5 Rights of Drug Administration.
Figure 16: 5 Rights of Drug Administration - Galbraith et al. (1994)
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Standing Order In my clinical situation a standing order for nebulised Salbutamol 5mg and Combivent 20mcg exists. This applies to any patient who presents to the practice nurse and meets all of the following criteria: •
Audible expiratory wheeze
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Shortness of breath
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Unable to complete full sentences
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Regular patient at this practice
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Diagnosed with Asthma
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Prior prescription and administration of Salbutamol 5mg and Combivent 20mcg in this practice
The patient must be assessed by the GP as soon as possible during or after the above drug therapy. This standing order appears to agree with the Asthma and Respiratory Society of New Zealand best practice guidelines in treating acute asthma (as shown in the diagram opposite).
Critical Analysis This standing order and 5 rights of drug administration do not include informed consent, preparation of the client or documentation after administration which I feel are integral in correct drug administration. It could be argued that presenting for treatment is consent. In that case I question whether it is truly informed? Pacific Pharmaceuticals Limited (2003) say that some patients receive an decreased and therefore ineffective dose of Salbutamol due to poor coordination and inhaler technique. This shows a need for patient education and alternative methods of administration such as a spacer. A similar issue around dose effectiveness is the venting of aerosol and nebuliser into the air. This begs the question - how are we able to measure the dose our patient receives? From this a need for checking equipment knowledge, dexterity, administration technique for both nurse and patient are apparent. 14
Figure 17: Management of Acute Asthma - The Asthma and Respiratory Foundation of New Zealand (2003).
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Recommendations to Colleagues Administration •
Have a good knowledge of your patient and their history (including allergies) and relate this to the drug being administered.
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Ensure that Salbutamol is prescribed correctly or you have a clear standing order.
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Have good knowledge of the equipment to administer Salbutamol.
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Ensure informed consent from the patient for giving Salbutamol.
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Use the 5 rights to ensure correct Salbutamol administration.
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Document the Salbutamol administration.
Monitoring •
Monitor stock levels - ensure that there is adequate supply and that it is all accounted for.
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Ensure Salbutamol is stored in conditions required by the manufacturer. Be aware that environmental temperature may alter particle size and therefore absorption of inhaled Salbutamol.
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Maintain a knowledge of your client and how their Asthma drug regime is working.
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Hold regular workshops for clients to learn about correct inhaler technique, spacers or other aids in Salbutamol administration. Use these sessions to monitor their technique and management of their asthma.
Conclusion This poster presentation has described the pharmacodynics and pharmacokinetics of Salbutamol and shown its potential effects on body systems. Authorisation for use and funding have been discussed as well as recommendations for administration and monitoring in clinical practice using best practice guidelines.
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References Apotex NZ Ltd (2003). APO-Salvent Sterules. Retrieved from Medsafe on 20 October 2003: http://www.medsafe.govt.nz/DatasheetPage.htm. Burgess, M. E. (1996). A Guide to the Law for Nurses and Midwives. Addison Wesley Longman New Zealand Ltd. Douglas Pharmaceuticals Ltd (2003). Buventol Easyhaler. Retrieved from Medsafe on 20 October 2003: http://www.medsafe.govt.nz/DatasheetPage.htm. Dr.Paul Communications Inc (2003). The Asthma Corner : What causes asthma? Retrieved from Dr.Paul Communications Inc on 14 October 2003 http://www.drpaul.com/asthma/asthma-causes.html. Dunn, R. J., Dilley, S. J., Brookes, J. G., Leach, D. S., Maclean, A. V., and Rogers, I. R., editors (2000). Emergency Medicine Manual. Venom Publishing, West Beach, 2nd edition. Galbraith, A., Bullock, S., and Manias, E. (1994). Fundamentals of Pharmacology. Addison-Wesley Publishing Company, Sydney. General Assembly of New Zealand in Parliament (1981). Medicines Act 1981. GlaxoSmithKline NZ Limited (2003a). Ventolin. Retrieved from Mesafe on 22 October 2003: http://www.medsafe.govt.nz/DatasheetPage.htm. GlaxoSmithKline NZ Limited (2003b). Ventolin infusion. Retrieved from Medsafe on 23 October 2003: http://www.medsafe.govt.nz/DatasheetPage.htm. 17
GlaxoSmithKline NZ Limited (2003c). Volmax. Retrieved from Medsafe on 22 October 2003: http://www.medsafe.govt.nz/DatasheetPage.htm. Katzung, B. G. (1998). Basic and Clinical Pharmacology. Appleton and lange, Stanford, 7th edition. Mann, J. (2000). Murder, magic and medicine. Oxford University Press. MEDSAFE (2003). Classification of of Medicines - Classification Process. Retrieved from Medsafe on 22 October 2003: http://www.medsafe.govt.nz/DatasheetPage.htm. Pacific Pharmaceuticals Limited (2003). ASMOL Inhaler. Retrieved from Medsafe on 20 October 2003: http://www.medsafe.govt.nz/DatasheetPage.htm. PHARMAC (2003). New Zealand Pharmaceutical Schedule. Retrieved from PHARMAC 24 September 2003 http://www.pharmac.govt.nz. Rang, H. P., Dale, M. M., Ritter, J. M., and Gardner, P. (1999). Pharmacology. Churchhill Livingstone, London, 4th edition. Spina, D., Page, C. P., Morley, J., and Mazzoni, L. (1997). Sublingual Absorption of Salbutamol in the Guniea-pig. Pulmonary Pharmacology and Therapeutics, 10, 67–69. The Asthma and Respiratory Foundation of New Zealand (2003). For Health Profs -> New Zealand Guidelines. Retrieved from The Asthma and Respiratory Foundation of New Zealand on 14 October 2003 http://www.asthmanz.co.nz.
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