Metabolism of amitriptyline in patients with chronic renal failure

Clinical Pharmacology Considerations in Pain Management in Patients with Advanced Kidney Failure

Pain is common and poorly managed in patients with advanced CKD, likely due to both under and over prescription of appropriate analgesics. Poorly managed pain contributes to patients' poor quality of life and excessive health care use. There is tremendous variability within and between countries in prescribing patterns of analgesics, suggesting that factors other than patient characteristics account for these differences. This article discusses the pharmacologic management of acute and chronic pain in patients with advanced CKD, and the role analgesics, including opioids, play in the overall approach to pain management.

Acute Pain Management Pharmacology for the Patient with Concurrent Renal or Hepatic Disease

The clinical utility of most analgesic drugs is altered in the presence of patients with impaired renal or hepatic function not simply because of altered clearance of the parent drug, but also through production and accumulation of toxic or therapeutically active metabolites. Some analgesic agents may also aggravate pre-existing renal and hepatic disease.

A search was performed, taking in published articles and pharmaceutical data to determine available evidence for managing acute pain effectively and safely in these two patient groups. The resulting information consisted mainly of small group pharmacokinetic studies or case reports, which included a large variation in degree of organ dysfunction.

In the presence of renal impairment, those drugs which exhibit the safest pharmacological profile are alfentanil, buprenorphine, fentanyl, ketamine, paracetamol (except with compound analgesics), remifentanil and sufentanil: none of these deliver a high active metabolite load, or suffer from significantly prolonged clearance. Amitriptyline, bupivacaine, clonidine, gabapentin, hydromorphone, levobupivacaine, lignocaine, methadone, mexiletine, morphine, oxycodone and tramadol have been used in the presence of renal failure, but do require specific precautions, usually dose reduction. Aspirin, dextropropoxyphene, non-steroidal anti-inflammatory drugs and pethidine, should not be used in the presence of chronic renal failure due to the risk of significant toxicity.

In the presence of hepatic impairment, most drugs are subject to significantly impaired clearance and increased oral bioavailability, but are poorly studied in the clinical setting. The agent least subject to alteration in this context is remifentanil; however the drugs’ potency has other inherent dangers. Other agents must only be used with caution and close patient monitoring. Amitriptyline, carbamazepine and valproate should be avoided as the risk of fulminant hepatic failure is higher in this population, and methadone is contraindicated in the presence of severe liver disease.

Pain in chronic kidney disease: a scoping review

There is increasing international attention in efforts to integrate palliative care principles, including pain and symptom management, into the care of patients with advanced chronic kidney disease (CKD). The purpose of this scoping review was to determine the extent, range, and nature of research activity around pain in CKD with the goal of (i) identifying gaps in current research knowledge; (ii) guiding future research; and (iii) creating a rich database of literature to serve as a foundation of more detailed reviews in areas where the data are sufficient. This review will specifically address the epidemiology of pain in CKD, analgesic use, pharmacokinetic data of analgesics, and the management of pain in CKD. It will also capture the aspects that pertain to specific pain syndromes in CKD such as peripheral neuropathy, carpal tunnel syndrome, joint pain, and autosomal dominant polycystic kidney disease.

Update on Psychotropic Medication Use in Renal Disease

Renal failure is a common medical condition, and many patients have comorbid psychiatric disorders. In this review, which is intended as a resource for consultation psychiatrists, the authors discuss pharmacokinetic considerations and provide information about the use of individual psychotropic medications in patients with renal disease. Most psychotropic medications are fat soluble, easily pass the blood-brain barrier, are not dialyzable, are metabolized primarily by the liver, and are excreted mainly in bile. Consequently, the majority of these drugs can be safely used with the end-stage renal disease population.

Treatment of Anxiety and Depression in Transplant Patients

Depressive and anxiety disorders appear during the transplant process due to psychological stressors, medications and physiological disturbances. Treatment is necessary to prevent impact on patient compliance, morbidity and mortality. Psychotropic medications provide an effective option, although most are only available as oral formulations. Because of this, they are more susceptible to alterations in pharmacokinetic behaviour arising from organ dysfunction in the pretransplant period. Kinetics are also an issue when considering potential drug-drug interactions before and after transplantation. Prior to transplant, organ dysfunction can change the pharmacokinetic behaviour of some psychotropic agents, requiring adjustment of dosage and schedules. Thoracic or abdominal organ failure may reduce drug absorption through disturbances in intestinal motility, perfusion and function. Cirrhotic patients experience increased drug bioavailability due to portosystemic shunting, and thus dosage is adjusted downward. In contrast, dosage needs to be raised when peripheral oedema expands the drug distribution volume for hydrophilic and protein-bound agents. Drug clearance for most psychotropic medications is dependent upon hepatic metabolism, which is often disrupted by endstage organ disease. Selection of drugs or their dosage may need to be adjusted to lower the risk of drug accumulation. Further adjustments in dosage may be called for when renal failure accompanies thoracic or abdominal organ failure, resulting in further impairment of clearance. Studies regarding the treatment of anxiety and depressive disorders in the medically ill are limited in number, but recommendations are possible by review of clinical and pharmacokinetic data. Selective serotonin reuptake inhibitors are well tolerated and efficacious for depression, panic disorder and post-traumatic stress disorder. Adjustments in dosage are required when renal or hepatic impairment is present. Among them, citalopram and escitalopram appear to have the least risk of drug-drug interactions. Paroxetine has demonstrated evidence supporting its use with generalised anxiety disorder. Venlafaxine is an alternative option, beneficial in depression, post-traumatic stress and generalised anxiety disorders. Nefazodone may also be considered, but there is some risk of hepatotoxicity and interactions with immunosuppressant drugs. Mirtazapine still needs to be studied further in anxiety disorders, but can be helpful for depression accompanied by anorexia and insomnia. Bupropion is effective in the treatment of depression, but data are sparse about its use in anxiety disorders. Psychostimulants are a unique approach if rapid onset of antidepressant action is desired. Acute or short-term anxiolysis is obtained with benzodiazepines, and selection of particular agents entails consideration of distribution rate, half-life and metabolic route.

The pharmacokinetics of tricyclic antidepressant drugs in the elderly

Antidepressants, especially tricyclic agents (TCAs), are increasingly used in geriatric patients since depression is a common mood disorder in the elderly and the size of elderly population is increasing. Notwithstanding the importance of kinetics to better use of drugs, its study in the elderly (regarding TCAs) is not sufficiently developed. The present paper briefly reviews the available data on amitriptyline, nortriptyline, protriptyline, imipramine, desipramine and clomipramine kinetics in the elderly.

Clinical pharmacokinetic considerations in the elderly. An update

There are numerous studies of drug handling in the elderly, but it is difficult to assess the significance of changes seen in vitro, or after single-dose administration, because they are often compensated by other mechanisms at steady-state. However, a knowledge of these studies is important as the results alert the investigator to possible treatment problems. The high incidence of adverse drug reaction in the elderly population leaves no doubt that improvements in therapy are needed. Research has been directed at seeking patterns of abnormality in the elderly on which to base recommendations for alterations in dosage regimens. The major shortcoming of this approach has been the failure to distinguish between the effect of chronological age on drug pharmacokinetics, and drug kinetics in elderly people with multiple pathology. The latter concern appreciates the variety of factors involved and the importance of treating each patient as an individual: presentation of mean data is confusing and misleading. The objective of drug treatment in any age group, but particularly in the elderly, is to administer the smallest possible dose which gives adequate therapeutic benefit throughout the entire dosage interval with the minimum of side effects. For most drugs the safe starting dose in the elderly is one-third to half that recommended in the young. Vigilance for potential side effects with plasma concentration monitoring, if available, should help keep toxicity to a minimum. When other medications are added or changed, the possibility of interaction should be anticipated. Methods for individualisation of dosage regimens and the use of sustained-release formulations in the elderly are discussed. Dosage alteration in the elderly in terms of reduced dose frequency, rather than dose size, may help improve compliance. A knowledge of the pharmacokinetics of a drug helps determine which approach will be most beneficial.