Drug therapy in geriatrics

Drug therapy in geriatrics

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  DRUG THERAPY IN GERIATRICS
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  DRUG THERAPY INGERIATRICS 1.Antibiotics agents: Benzathine Cefixime, Metronidazole, Fluconazole 2.Antiallergia agents: antihistamines, Steroids Decongestants 3.Antiasthma agents: corticosteroids, xolair theophylline, Leukotriene
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  4.Antihypertensive agents: thiazide diuretics,ACE inhibitors calcium channel blockers, beta blockers angiotensin 2 receptor antagonists 5.Diuretics agents: Loop diuretics furosemide, torsemide Thiazed diuretics epitizide, bendroflumethiazide Potassium sparing diuretics amiloride, triamterene spironolactones
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  DRUG THERAPY INGERIATRICS Definition: Geriatrics refers to the study of physical – pathophysiological and psychological aspects of the elderly. Geriatrics normally includes individuals of 65 years and above. The statistics have already reported that, the geriatric population has been increasing constantly worldwide. The phenomenal progress in the medical sector is a most prominent cause. Some diseases and disorders like hypertension, hypercholestremia, diabetes mellitus, osteoarthritis, impaired vision, hearing loss, etc. Drug interactions and disease drug interactions are more prevalent in the elderly due to multiple medicines being taken, patient related factors and the manner in which the doctor prescribes them.
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   Many elderlypatients may not able to adhere to the dosing schedules and the dosing instructions designed for them due to forgetfulness confusion, hearing, vision problems. This may lead either to overdosing of medicines that produces unwanted effects or reduced serum concentration due to missing of dose/does.  Before formulating drug therapy for the elderly, it is important for the physician to examine the medical history of the patient, the various disease that the patient has suffered throughout his/her lifetime, the medicines taken, any particular ingredients or drugs that he/she is allergic to and his/her lifestyle (smoking, drinking habits) etc.
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  Table 1 :Overall changes in body composition in the geriatric population Sr. No. Change 1 2 3 4 5 6 Reduced plasma albumin content. Reduced lean body mass. Reduced liver and renal mass. Reduced blood flow to major metabolizing organ. Reduced total body water and body size. Increase in total adipose tissue content.
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  Ageing results inmany physiological changes that could theoretically affect absorption. First pass metabolism, protein binding, elimination of drugs, age related changes in gastro intestinal tract, liver & kidney. Changes includes : → Gastric acid secretion. → Gastro intestinal motility. → Total surface area of absorption. → Liver size → Liver Blood flow → Glomerular filtration → Renal tubular filtration
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  PHARMACOKINETIC PARAMETERS A) Absorption: B)Distribution: C) Metabolism: D) Elimination: Creatinine clearance = (140 – Age) x weight in kgs / 72 x serum creatinine This equation applicable to patients from age 42 to 80. This equation is given by cock croft gault formula.
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  PHARMACODYNAMIC CONSIDERATIONS There areseveral pharmacodynamic changes observed with increasing age. These changes are mainly due to altered receptor sensitivity, affinity towards drug and number of receptors. It is observed that certain drugs like benzodiazepines shows enhanced activity (increased sedation) while some drugs like β-blockers shows diminished response (poor control of blood pressure), may be due to up-regulation and down regulation of receptors respectively. In general, pharmacodynamic interactions refer to the increased or decreased drug response in the body when drugs are administered alone or in combination with other drugs. These responses occur due to additive, synergistic or antagonistic effects between the drugs. For example: 1. Co-administration of benzodiazepines and chloropromazine cause increased sedation.
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  2. Aspirin andcoumarin anticoagulants may lead to bleeding. 3. Administration of NSAID’s like aspirin with digoxin can produce gastro-intestinal bleeding. ADVERSE REACTIONS IN THE ELDERLY The frequency and manifestations of adverse drug reactions in the geriatric population is widely different from that of adults due to the age associated changes in Pharmacodynamic pattern. The common ADR are described in Table 3.
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  Drug Interacting Drug Interaction NSAID’s DigoxinPrecipitation of toxicity especially cardiotoxicity of digoxin. Anti-anxiety drugs (Anxiolytics) Alcohol Enhanced sedation due to anxiolytics. Antidepressant Rifampicin, Carbamazepine Rifampicin and Carbamazepine being enzyme inducers, hasten the metabolism of the antidepressants thereby may cause its therapeutic failure. Anticonvulsants Ketoconazole, Erythromycin Exaggerated effect of anticonvulsants due to inhibition of cytochrome P-450 enzyme responsible for metabolising anticonvulsants. Antibiotics NSAID’s Vomitting, dizziness, stomach upset. Potassium sparing diuretics Potassium supplements Hyperkalemia Table:2 Common adverse drug reactions
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  ROLE OF PHARMACISTIN GERIATRIC CARE 1. Pharmacists are committed to optimizing pharmaceutical therapies for each patient to improve outcomes and reduce costs. 2. They are making significant contributions to the profession through specialized pharmaceutical care. 3. Pharmacists, aided by a comprehensive system employing information technology and clinical “best practices ” work with physicians to identify patients at risk for a given disease state and ensure that optimal drug therapy is received and unnecessary healthcare expenditures are eliminated. 4. Medications are probably the single most important healthcare technology in preventing illness, disability and health in the geriatric population.
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  General guidelines toprescribe drugs of elderly are mentioned below: • Assess the need of drug therapy. • Select drugs reported to be safe. • Avoid unsafe drugs. • Prepare dose and dosing schedule considering status of liver and renal system. • Select appropriate formulation that is easy to administered (e.g. liquid orals are easy compared to large tablets due to reduced salivary secretion.). • Record drug history carefully before prescriptions. • Try to reduce number of drugs. • Use alternative methods like hydrotherapy, massage etc. to a maximum possible extent.
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  Conclusions: 1) Limit –Range 2) Reduce – Dose 3) Review – Regularly 4) Explain – clearly
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  •References: • British NationalFormulary 49 March, 2005.page no 17 to 18 • Text book of basic and clinical pharmacology by Bertram G.Katzung 6th Edition, page no.923 to 931. • Text book of general pharmacology by Dr. N. S. Vyawahare Saloni.Vora page no. 11.1 to 11.7. • Text book of clinical pharmacy and therapeutics by Rogerwalker cate whittlesea 4th Edition page no.135 to 138. •www.wikipedia.com
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