Practitioner
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Under the microscope:The dangers of prescribing loop diuretics for older menLoop diuretics may increase the loss of bone mass in older male patients an American study has shown. The paper, published in the April 14 issue of Archives of Internal Medicine, suggests prolonged use of the drugs may reduce the bone mass density (BMD) in the hips of older men. Loop diuretics are often prescribed for sufferers of heart failure and/or hypertension and so are commonly used by older patients. They can cause a loss of calcium through the urine and result in bone loss. The study of over 3000 men aged 65 and over found the greatest loss of BMD in continual users of the drugs. “Compared with rates of hipbone loss among nonusers of diuretics, adjusted rates of loss were about two-fold greater among intermittent loop diuretic users and about two and a half-fold greater among continuous loop diuretic users,” the study authors said. “These results suggest that the potential for bone loss should be considered when loop diuretics are prescribed to older patients in clinical practice.” Practice Pearl Furosemide is the most prescribed generic medicine in community living men aged 65 and over. As well as improving the symptoms of heart disease and high blood pressure it can increase the loss of calcium through the urine. Thiazide diuretics can promote the renal recovery of calcium and may improve BMD. PDUK’s Rationale Prescribing: Cardiac Drugs course will help you prescribe more effectively for patients with cardiovascular disease. This interactive day covers hypertension, angina, cardiac failure, vascular disease and important new drug developments. It will ensure you are up-to-date with prescribing information and help you meet the increasing demands of prescribing within the NHS. For further details, click here. On the case:An elderly patient with chronic COPDPaul Pepperman is a 72-year-old man with chronic COPD. He is on the following medication:
What is the rationale for Mr Pepperman’s medication? The rationales discussed here do not examine every avenue of each treatment but are intended to draw the reader’s attention to some main points. NICE and BTS guidelines examine these rationales in more depth. Combivent inhalerAs we age the number of beta-2-adrenoceptors in our lungs decreases. This, along with variations in the reversibility of airflow obstruction, means the response to short acting beta-2-agonists can be variable. Combivent is a combination of ipratropium plus salbutamol. The combination of the two drugs has been found to modestly but significantly increase FEV1 compared with monotherapy. CarbocisteineMucolytics such as carbocisteine reduce the viscosity of sputum in a number of ways. They alter mucous production and also have antibacterial, immunostimulatory and antioxidant effects. Whilst mucolytics are relatively expensive, and blanket use in all patients with COPD would not be cost effective, it may be of use in some patients if they have a chronic productive cough. Cochrane performed a systematic review and found mucolytics could reduce the number of exacerbations in COPD patients by 20% if given over the winter months (0.6 fewer exacerbations a year). DoxycyclineCOPD exacerbations may be bacterial or viral. Bacterial infections tend to be Streptococcus pneumoniae, Haemophilus influenza or Moraxella catarrhalis. Antibacterial treatment is required when the sputum becomes purulent or if there are other signs of infection. Amoxicillin is usually the first choice treatment for Haemophilus influenza or uncomplicated community acquired pneumonia but this patient may be allergic to penicillin. Erythromycin is another choice but this may affect the other drugs as erythromycin inhibits the metabolism of theophylline leading to increased plasma concentrations of theophylline and toxicity. Additionally, oral erythromycin may also decrease (and possibly render ineffective) plasma-erythromycin concentrations. Tetracycline is indicated for some respiratory system infections. Doxycycline is not explicitly listed in table 5.1 (summary of antibacterial therapy) as a treatment but, microbiologically, it has a similar action to tetracycline. It is important to ensure Mr. Pepperman knows how to take the doxycycline correctly, in particular to take it sitting or standing with plenty of water. Slo-phyllinSlo-phyllin contains theophylline, a methylxanthine. Whilst the pharmacodynamic action of theophylline is not fully understood it does have a weak bronchodilator activity, anti-inflammatory activity and may improve diaphragm muscle strength. The normal therapeutic range is 10-20 mg/L but it may have anti-inflammatory effects on COPD at 5-10mg/L. There is some evidence that suggests clinical improvement when used together with ipratropium (or long-acting beta-2-agonists). NICE recommends they should only be used after short and long-acting beta-2-agonist have been trialled or the patient cannot use inhalers. Theophylline can be difficult to manage in practice because of its narrow therapeutic range and the large number of factors that can influence its clearance. It has been prescribed by brand because there is wide variation in the bioequivalence between the various preparations available. The COPD worsens…Mr Pepperman has a non-infective exacerbation of his COPD and needs to be admitted to hospital. He has increased shortness of breath and respiratory rate, his pulse rate is raised and his oxygen saturations reduced. On admission his theophylline level is found to be 7mg/L. It is decided to increase his Slo-phylline dose to 500mg bd. His combivent inhaler is stopped and he is started on regular salbutamol nebulas, prednisolone and a tiotropium inhaler. What is the rationale behind the changes to his medication? For further discussion of Mr Pepperman’s case and other thought provoking scenarios sign up for PDUK’s Rational Prescribing for Airway Disease. Click here. In brief...PDUK runs a range of pharmacology-focused workshops. These include:
Ask PDUKMark Magas is a pharmacist and senior university lecturer. Omar Ali is a prescribing consultant for primary care. He lectures in applied therapeutics and is a formulary development pharmacist. They answer your questions below. What is the SMART strategy in the treatment of asthma?Previously no patient treated for asthma was without a short acting beta-2-agonist whatever their treatment or symptoms. Symbicort Maintenance And Reliever Therapy (SMART) allows patients to manage persistent asthma using one inhaler both for relief and maintenance. The patient takes their maintenance dose morning and night but can use up to 10 extra puffs each day for relief (12 puffs daily in total). Formoterol is a long acting beta-2-agonist but unlike other drugs such as salmeterol it has a rapid onset of action making it suitable for use as a reliever. Why do patients taking amiodarone require thyroid function tests before beginning treatment?Amiodarone is often used when other antiarrhythmic drugs have failed or their use is contra-indicated. Hyperthyroidism can cause arrhythmias and should therefore be eliminated as a possible source before starting such a treatment. Also amiodarone contains iodine within the drug molecule and can cause thyroid function disorders. Even if hyperthyroidism isn’t the reason for the arrhythmia, a baseline and monitoring of thyroid function will need to be ongoing. I recently had a patient with a history of myocardial infarction (MI). His left ventricular function had not been compromised and he had no symptoms. He was not on a beta-blocker - is this good practice?According to NICE guidelines (2007) patients with a proven history of MI that still have preserved left ventricular function and are asymptomatic should not be routinely offered treatment with a beta-blocker. Patients must not have been identified to be at increased risk of further cardiovascular events and have no other compelling indications for beta-blocker treatment. |