Pharmacokinetic and pharmacodynamic properties of tramadol IR and SR in elderly patients: a prospective, age-group-controlled study

Clinical report of delayed recovery after general anaesthesia in elderly patients with cervical spine surgery: A case report

This report describes a case of a 70-year-old male that underwent decompression laminectomy and internal fixation under general anaesthesia. After extubation, the patient gradually developed no response to instructions and the disturbance of consciousness persisted with unequal pupils in size, but clinical neurological findings and a brain computed tomography scan showed no organic abnormalities. A careful medical history undertaken by anaesthesiologists revealed that the patient had a history of trauma to his left eye, resulting in blindness in this eye, but the surgeons, anaesthesiologists and nurses did not find these problems before the operation. The diagnosis in this case was prolonged unconsciousness due to delayed recovery from anaesthesia. Careful titration of the dose based on individual response in order to reduce adverse effects of general anaesthetics is especially important in elderly patients. Multiple checks of the patient information, surgical safety checklist and medical history by anaesthesiologists, surgeons and nurses can minimize the chance of an adverse outcome.

Chronic Pain in the Elderly: Mechanisms and Perspectives

Chronic pain affects a large part of the population causing functional disability, being often associated with coexisting psychological disorders, such as depression and anxiety, besides cognitive deficits, and sleep disturbance. The world elderly population has been growing over the last decades and the negative consequences of chronic pain for these individuals represent a current clinical challenge. The main painful complaints in the elderly are related to neurodegenerative and musculoskeletal conditions, peripheral vascular diseases, arthritis, and osteoarthritis, contributing toward poorly life quality, social isolation, impaired physical activity, and dependence to carry out daily activities. Organ dysfunction and other existing diseases can significantly affect the perception and responses to chronic pain in this group. It has been proposed that elderly people have an altered pain experience, with changes in pain processing mechanisms, which might be associated with the degeneration of circuits that modulate the descending inhibitory pathways of pain. Aging has also been linked to an increase in the pain threshold, a decline of painful sensations, and a decrease in pain tolerance. Still, elderly patients with chronic pain show an increased risk for dementia and cognitive impairment. The present review article is aimed to provide the state-of-art of pre-clinical and clinical research about chronic pain in elderly, emphasizing the altered mechanisms, comorbidities, challenges, and potential therapeutic alternatives.

Evaluation of tramadol human pharmacokinetics and safety after co-administration of magnesium ions in randomized, single- and multiple-dose studies

BACKGROUND

Magnesium ions (Mg2+) increase and prolong opioid analgesia in chronic and acute pain. The nature of this synergistic analgesic interaction has not yet been explained. Our aim was to investigate whether Mg2+ alter tramadol pharmacokinetics. Our secondary goal was to assess the safety of the combination.

METHODS

Tramadol was administered to healthy Caucasian subjects with and without Mg2+ as (1) single 100-mg and (2) multiple 50-mg oral doses. Mg2+ was administered orally at doses of 150 mg and 75 mg per tramadol dosing in a single- and multiple-dose study, respectively. Both studies were randomized, open label, laboratory-blinded, two-period, two-treatment, crossover trials. The plasma concentrations of tramadol and its active metabolite, O-desmethyltramadol, were measured.

RESULTS

A total of 25 and 26 subjects completed the single- and multiple-dose study, respectively. Both primary and secondary pharmacokinetic parameters were similar. The 90% confidence intervals for Cmax and AUC0-t geometric mean ratios for tramadol were 91.95-102.40% and 93.22-102.76%. The 90% confidence intervals for Cmax,ss and AUC0-τ geometric mean ratios for tramadol were 93.85-103.31% and 99.04-105.27%. The 90% confidence intervals for primary pharmacokinetic parameters were within the acceptance range. ANOVA did not show any statistically significant contribution of the formulation factor (p > 0.05) in either study. Adverse events and clinical safety were similar in the presence and absence of Mg2+.

CONCLUSIONS

The absence of Mg2+ interaction with tramadol pharmacokinetics and safety suggests that this combination may be used in the clinical practice for the pharmacotherapy of pain.

Chronic Pain Management in the Elderly

Chronic pain is extremely prevalent in older adults and is associated with significant morbidity, including limited mobility, social isolation, and depressed mood. Pain is defined by a biopsychosocial model highlighting the importance of a multidisciplinary approach to treatment, including multimodal medications, selected interventions, physical therapy and rehabilitation, and psychological treatments. In this narrative review, the authors highlight the use of these approaches in older adults with specific attention paid to considerations unique to aging, including alterations in drug metabolism, avoidance of polypharmacy, and physiologic changes predisposing to painful conditions.

Population Pharmacokinetic/Pharmacodynamic Modeling of O-Desmethyltramadol in Young and Elderly Healthy Volunteers

BACKGROUND

Age-related changes in the concentration-effect relationship of (+)-O-desmethyl-tramadol [(+)-ODM], tramadol's active metabolite, are not documented in the elderly.

OBJECTIVE

The objective of this study was to characterize, in elderly and young subjects, the (+)-ODM pharmacokinetic and pharmacodynamic relationship to examine the effect of age after single-dose administration of tramadol 200 mg extended-release tablets.

METHODS

A population analysis of a double-blind, randomized, placebo-controlled, two-period cross-over study including 13 elderly (aged ≥75 years) subjects with mild renal insufficiency and 16 young (aged 18-40 years) subjects was conducted. For 48 h post-dose, blood samples were collected and pain tolerance thresholds measured using an electrically stimulated pain model. A pharmacokinetic/pharmacodynamic model incorporating a one-compartment pharmacokinetic model for (+)-ODM parameterized with first-order formation rate, clearance (CL/f_m), volume of distribution (V/f_m) and a sigmoid maximum effect (E_max) model incorporating baseline (E₀) and placebo effect was used.

RESULTS

Maximum plasma concentrations of (+)-ODM occurred later and plasma concentrations declined more slowly in the elderly than in young subjects. In the elderly, V/f_m was 76% larger and CL/f_m 16% slower. Baseline (E₀) and sensitivity (C₅₀) for pain tolerance were similar between young and elderly subjects. However, the E_max parameter was 2.5 times higher in the elderly and maximum possible treatment-related effect was 169 (135-221) in the young and 194 (149-252) in the elderly; that is, 15% higher in the elderly.

CONCLUSIONS

This exploratory analysis suggests that age-related differences exist in the distribution and elimination of (+)-ODM, including a 76% larger distribution outside the central compartment and 16% slower clearance of (+)-ODM. These pharmacokinetic changes are associated with a 15% higher maximum possible treatment-related effect and carry the potential for greater efficacy but also the potential for increased side effects at the same dose in elderly subjects. Clinicaltrials.gov identifier: NCT02329561.

The Role of Opioid Analgesics in Geriatric Pain Management

When possible, chronic noncancer pain (CNCP) in older adults should be managed by nonpharmacologic modalities in conjunction with nonopioid analgesics. If moderate-to-severe pain persists despite these approaches, however, nonparenteral opioids may be considered as adjunctive therapy. This article reviews the epidemiology of opioid use and their effectiveness for CNCP in older adults and summarizes important age-related changes in opioid pharmacokinetics and pharmacodynamics that increase the risks of adverse effects in the elderly. Finally, to assist clinicians with selecting appropriate therapy, the article concludes with an evidence-based approach to optimize opioid prescribing in older adults with CNCP.

Pharmacokinetics of Tramadol and O-Desmethyltramadol Enantiomers Following Administration of Extended-Release Tablets to Elderly and Young Subjects

BACKGROUND

Tramadol is frequently used in geriatric patients; however, pharmacokinetic (PK) publications on tramadol and O-desmethyltramadol (ODM) in elderly patients are rare.

OBJECTIVE

Our objective was to characterize the PK of tramadol and ODM, including absorption processes and covariates for tramadol, in elderly and young subjects after single-dose administration of 200-mg extended-release tablets.

METHODS

We conducted a PK study in 15 elderly (aged ≥75 years) subjects with mild renal insufficiency and 20 young (18-40 years) subjects; blood and urine samples were collected for 48 h post-dose. Non-compartmental analysis (NCA) of each tramadol and ODM enantiomer included area under the concentration-time curve (AUC), terminal elimination rate (k el), total body clearance, volume of distribution (V area/ F), and renal clearance (Clr0-48). A one-compartment population model of total tramadol concentration was parameterized with clearance (CL/F), volume of distribution (V/F), and mixed order absorption (first-order and zero-order absorption rate constants with lag times).

RESULTS

NCA demonstrated comparable maximum plasma concentration (C max) and AUC between age groups for tramadol enantiomers, but significant differences in V area/ F (mean 34% higher) and k el (mean 28% lower) in the elderly. PK of ODM were significantly different in the elderly for AUC0-inf (mean 35% higher), Clr0-48 (mean 29% lower), and k el (mean 33% lower). The population analysis identified age as a covariate of V/F (young 305 L; elderly 426 L), with a 50% longer mean elimination half-life in the elderly. No differences in absorption processes were observed.

CONCLUSIONS

Tramadol exposure was similar between the age groups; exposure to ODM was higher in elderly subjects.

Breakthrough pain in elderly patients with cancer: treatment options

The prevalence of pain is high in the elderly and increases with the occurrence of cancer. Pain treatment is challenging because of age-related factors such as co-morbidities, and over half of the patients with cancer pain experience transient exacerbation of pain that is known as breakthrough pain (BTP). As with background pain, BTP should be properly assessed before being treated. The first step to be taken is optimizing around-the-clock analgesia with expert titration of the painkiller. Rescue medication should then be provided as per the requested need, while at the same time preventing identified potential precipitating factors. In the elderly, starting treatment with a lower dose of analgesics may be justified because of age-related physiological changes such as decreased hepatic and renal function. Whenever possible, oral medication should be provided prior to a painful maneuver. In the case of unpredictable BTP, immediate rescue medication is mandatory and the subcutaneous route is preferred unless patient-controlled analgesia via continuous drug infusion is available. Recently, transmucosal preparations have appeared in the medical armamentarium but it is not yet known whether they represent a truly efficient alternative, although their rapid onset of activity is already well recognized. Adjuvant analgesics, topical analgesics, anesthetic techniques and interventional techniques are all valid methods to help in the difficult management of pain and BTP in elderly patients with cancer. However, none has reached a satisfying scientific level of evidence as to nowadays make the development of undisputed best practice guidelines possible. Further research is therefore on the agenda.

An iatrogenic metabolic encephalopathy in a nonagenarian: The dilemma of a critical miss as a possible social dismissal

Here we posit for discussion the example of a reversible metabolic encephalopthy in a very elderly male that was missed clinically. A metabolic encephalopathy in extrememly elderly patients may be confused with delerium or inattention. A reversible cause of cognative dysfunction in the aged may be missed by practitioners because the aged may be assumed to have some level of impaired cognition; this may lead to a “social dismissal” of mental status changes. We highlight the need for engaged physicians in the care of the aged and vigilance against a professional bias toward the elderly patient that is dismissive.

Adverse effects of analgesics commonly used by older adults with osteoarthritis: focus on non-opioid and opioid analgesics

BACKGROUND

Osteoarthritis (OA) is the most common cause of disability in older adults, and although analgesic use can be helpful, it can also result in adverse drug events.

OBJECTIVE

To review the recent literature to describe potential adverse drug events associated with analgesics commonly used by older adults with OA.

METHODS

To identify articles for this review, a systematic search of the English-language literature from January 2001 to June 2012 was conducted using PubMed, MEDLINE, EBSCO, and the Cochrane Database of Systematic Reviews for publications related to the medical management of OA. Search terms used were "analgesics," "acetaminophen," "nonsteroidal anti-inflammatory drugs" (NSAIDs), "opioids," "pharmacokinetics," "pharmacodynamics," and "adverse drug events." The search was restricted to those articles that concerned humans aged ≥65 years. A manual search of the reference lists from identified articles and the authors' article files, book chapters, and recent reviews was conducted to identify additional articles. From these, the authors identified those studies that examined analgesic use in older adults.

RESULTS

There are limited data to suggest that non-frail elders are more likely than their younger counterparts to develop acetaminophen-induced hepatotoxicity. However, decreased hepatic phase II metabolism in frail elders may result in increased risk of hepatotoxicity. It is now well established that older adults are at higher risk of NSAID-induced gastrointestinal toxicity and renal insufficiency. Insofar as opioids, the data that suggest an increased risk of falls, fractures, or delirium need to be tempered by the potential risk of inadequately treating severe chronic OA-related pain.

CONCLUSIONS

Acetaminophen is the mainstay frontline analgesic for treating OA-related pain in older adults. NSAIDs should be limited to short-term use only, and for moderate to severe OA-related pain, opioids may be preferable in individuals without substance abuse or dependence issues.

Pharmacological Management of Cancer Pain in the Elderly

Existing studies indicate a high prevalence rate and poor management of cancer pain in the elderly. Pain is often considered an expected concomitant of aging, and older patients are considered more sensitive to opioids. Despite the well known pharmacokinetic changes in the elderly, the complex network of factors involved in the opioid response make the evaluation of a single element, such as age, more difficult. Notwithstanding such difficulties, appropriate analgesic treatment is able to control cancer pain in the elderly in most cases. Skills necessary to optimise pain control in older cancer patients include the ability to objectively assess functional age (not necessarily related to chronological age since the rate of decline is variable), understand the impact of coexisting conditions, carefully manage the numbers and types of drugs taken at the same time and adequately communicate with patients and relatives. The most common treatment of cancer pain consists of the use of regularly given oral analgesics. The elderly are at increased risk of developing toxicity from NSAIDs, and the overall safety of these drugs in frail elderly patients should be considered. When older patients have clear contraindications to NSAIDs, manifest signs of toxicity from these agents, or find that pain is no longer controlled with this class of drugs, opioids should be started. A variety of opioids are available, and they differ widely with respect to analgesic potency and adverse effects among the elderly. Although the aged population requires lower doses of opioids, only careful titration based on individual response can ensure the appropriate response to clinical demand. Elderly patients are potentially more likely to be affected by opioid toxicity because of the physiological changes associated with aging. Nevertheless, appropriate dosage and administration may limit these risks. Cancer patients with pain who do not respond to increasing doses of opioids because they develop adverse effects before achieving acceptable analgesia may be switched to alternative opioids. Despite the favourable effects reported with opioid switching, monitoring is crucial, particularly in the elderly or patients who are switched from high doses of opioids. Adjuvant analgesics, including antidepressants, antiepileptics, corticosteroids and bisphosphonates may help in the treatment of certain types of chronic pain. With an appropriate and careful approach, it should be possible to reduce or eliminate unrelieved cancer pain in most elderly patients and, consequently, to enhance their quality of life. Older patients with cancer should be continuously assessed for cancer pain, both before and after analgesic treatment.