Aging Biology and Geriatric Clinical Pharmacology - Assignment Example

Name: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Institution: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Professor: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Course: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Date of Submission: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Answering part B from the manual uploaded 1. How does an ageing nervous system adapt to the years of challenge set upon itself by our daily activities? What are the consequences? There are different levels at which the nervous system changes with ageing. They include: structural changes, chemical changes, and functional changes (Mattson & Magnus, 2006, pg 54). Each of this aspect of change involves different alterations in the functioning of the nerves. The changes in overall affect the normal functioning of the body in terms of sleep patterns, memory function as well as sensory and motor elements. In addition, they may result to risks in neurological and psychiatric related complications (Mattson & Magnus, 2006, pg 59). Age related structural changes in the nervous system deal with the number of cells, the neurons as well as synapses. The changes also have an effect on the neural network hence resulting to death of cells that link with the brain by means of pathways. Consequently, the brain of the aged suffers cell loss. The reduced reserve capacity causes delirium during stress as well as changes in memory and other functions (Mattson & Magnus, 2006, pg 76). On the other hand, age related biochemical changes involve alterations in the neurotransmitters. Neurotransmitters are involved in conduction of messages from one neurone to another. They do this in conjunction with synapses (Mattson & Magnus, 2006, pg 83). The biochemical changes affect the necessary balance in the neurotransmitters that negatively impacts on their fine tuning role (Mattson & Magnus, 2006, pg 84). Age related functional changes in the nervous system will affect the memory (Mattson & Magnus, 2006, pg 84). Functional changes as a result of ageing will generally impact on the aged people’s ability to acquire memory and store information. In addition, changes in the nervous system as a result of age will affect people’s daily activities and normal body function like sleeping. The changes might also lead to incidences of psychiatric and neurological disorders. They may also affect hearing (presbycusis) or sight (miosis). 2. Hormones are essential molecules for normal activity and function of the body. As hormone producing organs age numerous changes occur in the production and secretion of hormones. What implications do these changes have on the body? There are three types of age related changes occur within the endocrine glands on the body. Those are anatomical, functional and pathological changes. Anatomical changes lead to loss of the endocrine tissue hence affecting the amounts of the hormone secreted. Functional changes on the other hand will entail those changes that happen to the ovary of the aged people. This factor will impact on the secretion of oestrogen, lowering its levels in the body. The consequence is production of GnRH that increases the secretion of FSH. Production of FSH will lead to egg development within the ovary (Chahal & Drake, 2007, pg 67). Another very common endocrinological change in ageing women is menopause. Being a functional change, it has been seen to affect the function of the gland. Menopause can be explained by way of two propositions. One is that as women age, the eggs in the ovary will be exhausted. This way, the changes are viewed as anatomical. Alternatively, menopause can be seen to be as a result of the loss or reduced hormonal stimulus supplied by the hormones. This way, the explanation is taken to be taking on a functional change. As people age, they lose the endocrine tissue. Consequently, there will be low production of hormones in the body. This culminates into death of cells, impairment of the immune system, changes in the neoplastic as well as vascular modifications (Chahal & Drake, 2007, pg 64). It might also lead to fibrosis condition. Functional changes occur as a result of reduced production of hormones (Chahal & Drake, 2007, pg 69). This is attributed to low stimuli for the production of the particular hormone. An example of such a case is in the production of oestrogen. If the hormone that triggers the production of oestrogen is not secreted, then oestrogen will be absent in which case, formation of the ova will be hampered resulting to menopause (Chahal & Drake, 2007, pg 74). For instance, changes in the receptor numbers and conditions could result non-insulin dependent (Type II) diabetes mellitus. This condition is non insulin dependent. Unlike hormone deficiencies, changes in the numbers and conditions of the receptors cannot be handled by giving supplements to the aged person (Chahal & Drake, 2007, pg 76). Menopause leads to osteoporosis that may come with frequent fractures. The fractures contribute to the dowager’s hump characteristic of ageing women. 3. The geriatric dosing axiom, “start low and go slow” is based on pharmacokinetic considerations and concern for adverse drug reactions and not from clinical trial data. Clinical data is usually obtained from much younger subject cohorts. Discuss the implications There have been several studies of the pharmacokinetics of excreted drugs and aging (Mclean & Le Couterur, 2004 pg 56). According to this study the pharmacokinetics of excreted drugs are not affected by the aged to any clinical extent (Mclean & Le Couterur, 2004 pg59). In contrast, when adverse drug reactions occur in the aged, they are more likely to be severe and less likely to be reported or recognized by the patient (Mclean & Le Couterur, 2004 pg 78). In addition, one of the significant factors associated with adverse drug reactions is polypharmacy (Mclean & Le Couterur, 2004 pg 79). Aging is related to increased risk of adverse drug reactions to specific classes of drugs that are independent of altered pharmacokinetics and polypharmacy (Mclean & Le Couterur, 2004 pg 84). On the contrary, older people are improperly represented in clinical trials with up to 35% of published trials excluding older people on the basis of age without explanation (Mclean & Le Couterur, 2004 pg 84). For example, around one-half of cases of breast cancer occur in women aged 65 years and over, this age group represents only 9% of subjects enrolled in breast cancer trials (Mclean & Le Couterur, 2004 pg 87). Moreover, exclusion of older patients from trials appears to avoid perceived problems linked with compliance, confounding morbidities, and adverse drug reactions (Mclean & Le Couterur, 2004 pg 85). Given the practical difficulties of studying the aged in randomized clinical trials, alterative methods for determining risk-benefit ratios need to be considered (Mclean & Le Couterur, 2004 pg 89). The drugs’ absorption, distribution and metabolism as well as their excretion are all impacted by the ageing process. Among the aged people, there are characteristic problems about their stomachs as well as their intestines. This hampers proper absorption that usually happens in these areas. Ailments associated with the aged will also affect adequate absorption needed. In addition, higher body fats and low body water will affect the drug distribution. Similarly, plasma protein binding will hinder good distribution of drugs in the aged people’s bodies. Among the aged people, the metabolic rates are significantly low due to their reduced liver activity. Another area that is of concern in pharmacology about the aged is their excretion. Within the old people, the kidney function is highly impaired. Since little blood goes to the kidney, there is high likelihood that drugs will not be removed from the blood there. Implications Studies have shown that over 75% of people aged 75 or more use prescriptive drugs in the UK (McLean & Couteur, 2004, pg 65). On the other hand, the concern is whether the drugs are well administered, or whether indeed the drugs suit the aged people’s health demands. This is because, in yet another study, 12.5% of the aged who get admitted are as a result of drug treatment related issues (McLean & Couteur, 2004, pg 66). Some of those who get admitted are due to adverse effects. Research also shows that people aged 60-70 years are two times more vulnerable to adverse effects than young ones. In conclusion, geriatric dosing axiom, “start low and go slow” is based on pharmacokinetic considerations and concern for adverse drug reactions and not from clinical trial data. Clinical data is usually obtained from much younger subject cohorts of ages from age 18-40 (McLean & Couteur, 2004, pg 73).This means that the old people will not have drugs that cater for their needs. With ageing, the old people experience changes that alter the normal drug assimilation, circulation, breakdown and secretion. These processes are relatively higher and better in young people that they are among the old. Giving old people drugs whose normal doses are determined on the results of tests on people in the 18 - 40 age group, does not only make the drugs useless to the old people’s bodies but also risk putting the old in danger of other diseases, adverse effects, or even death. It is also likely that there will be lack of compliance by the old patients (McLean & Couteur, 2004, pg 75). References: McLean, A. & Couteur, D. 2004. Aging biology and geriatric clinical pharmacology. “Pharmacological Reviews” Chahal, H. & Drake, W. 2007. The endocrine system and ageing “Journal of Pathology” Mattson, M. & Magnus, T. 2006. Ageing and neuronal vulnerability. “Nature Reviews Neuroscience” Read More