Heterocyclic antidepressant, monoamine oxidase inhibitor and neuroleptic withdrawal phenomena

Dependence, withdrawal and rebound of CNS drugs: an update and regulatory considerations for new drugs development

The purpose of this article is to describe dependence and withdrawal phenomena related to CNS drugs discontinuation and to clarify issues related to the evaluation of clinical drug withdrawal and rebound as they relate to safety in new drug development. The article presents current understanding and definitions of drug dependence and withdrawal which are also relevant and important features of addiction, though not the same. Addiction, called substance use disorder in DSM-5, affects an individual’s brain and behaviour, represents uncontrollable drug abuse and inability to stop taking a drug regardless of the harm it causes. Characteristic withdrawal syndromes following abrupt discontinuation of CNS-active drugs from numerous drug classes are described. These include drugs both scheduled and non-scheduled in the Controlled Substances Act, which categorizes drugs in five schedules based on their relative abuse potentials and dependence liabilities and for regulatory purposes. Schedules 1 and 2 contain drugs identified as those with the highest abuse potential and strictest regulations. Less recognized aspects of drug withdrawal, such as rebound and protracted withdrawal syndromes for several drug classes are also addressed. Part I presents relevant definitions and describes clinical withdrawal and dependence phenomena. Part II reviews known withdrawal syndromes for the different drug classes, Part III describes rebound and Part IV describes protracted withdrawal syndromes. To our knowledge, this is the first compilation of withdrawal syndromes for CNS drugs. Part V provides details of evaluation of dependence and withdrawal in the clinical trials for CNS drugs, which includes general design recommendations, and several tools, such as withdrawal questionnaires and multiple scales that are helpful in the systematic evaluation of withdrawal. The limitations of different aspects of this method of dependence and withdrawal evaluation are also discussed.

Intoxications with the monoamine oxidase inhibitor tranylcypromine: an analysis of fatal and non-fatal events

Tranylcypromine (TCP) is a non-selective and irreversible monoamine oxidase inhibitor and an effective agent in the treatment of major depression. It features a complex pharmacologic profile and overdoses might induce severe intoxications. To identify typical clinical presentations of TCP-intoxications, range of associated TCP-dosages and possible differences between fatal and non-fatal intoxications a systematic review of all previously published cases of TCP-intoxications was conducted. We detected n=20 reports of TCP-intoxications in the literature (fatalities n=10). Mean age was 36.7 years (median 37); the majority of patients were female (60%). Frequent findings in patients with TCP-intoxications were disturbance of consciousness/cognitive dysfunction (90%), cardio-vascular symptoms (55%), hyperthermia (50%), respiratory distress (45%), delirium (45%), muscular rigidity (30%) and renal failure (20%). Suicidal intent was present in n=18 (90%) patients. First clinical symptoms related to TCP-intoxication developed on average in less than 1 day. The average dosage related to TCP-intoxication was 677 mg. The highest survived TCP-dosage was 4000 mg and the lowest fatal dosage was 170 mg. Patients with fatal intoxications were on average older (40.5 vs. 32.8 years) and developed a more rapid onset of symptoms (0.2 vs. 0.8 days). Death occurred after a mean time of 0.6 days; symptom relief in patients with non-fatal intoxications developed on average after 3.2 days. Considering the large dose spectrum between survived and lethal TCP-dosages individual susceptibility factors might play a role regarding the severity of clinical symptoms independently of the ingested dosage.

Challenges in pharmacologic management of the hospitalized patient with psychiatric comorbidity

BACKGROUND

Psychiatric comorbidity is common in the inpatient medical population. Hospitalists are frequently faced with decisions regarding the psychopharmacologic management of medically ill patients, yet receive limited psychiatric training. This review aims to assist the hospitalist in making an informed decision about the continuation of home psychotropic medications in the medically ill patient.

METHODS

A PubMed literature review was performed to obtain information on the effects of psychotropic medication discontinuation. In addition, the literature was reviewed regarding the potential challenges of psychotropic medication continuation.

RESULTS

A growing number of studies demonstrate high rates of relapse when medications are discontinued in patients suffering from mood disorders, schizophrenia, and anxiety disorders. Abrupt cessation of psychotropics is especially dangerous, leading to a greater chance of destabilization. Discontinuation syndromes, with prominent physical symptoms, may also result from sudden psychotropic cessation. Conversely, continuing home psychotropic medication may cause adverse effects due to drug-drug interactions or changing pharmacokinetics.

CONCLUSIONS

This review examines the risks of psychotropic discontinuation as well as the challenges of psychotropic continuation in the medically ill patient. When making complex psychopharmacologic decisions, hospitalists should employ all available resources, including pharmacists and consult-liaison psychiatrists. Ultimately, physicians and patients must make collaborative decisions, weighing the risks and benefits of psychiatric medications.

The mechanisms of tolerance in antidepressant action

There is increasing awareness that, in some cases, long-term use of antidepressant drugs (AD) may enhance the biochemical vulnerability to depression and worsen its long-term outcome and symptomatic expression, decreasing both the likelihood of subsequent response to pharmacological treatment and the duration of symptom-free periods. A review of literature suggesting potential side effects during long treatment with antidepressant drugs was performed. Studies were identified electronically using the following databases: Medline, Cinahl, PsychInfo, Web of Science and the Cochrane Library. Each database was searched from its inception date to April 2010 using "tolerance", "withdrawal", "sensitization", "antidepressants" and "switching" as key words. Further, a manual search of the psychiatric literature has been performed looking for articles pointing to paradoxical effects of antidepressant medications. Clinical evidence has been found indicating that even though antidepressant drugs are effective in treating depressive episodes, they are less efficacious in recurrent depression and in preventing relapse. In some cases, antidepressants have been described inducing adverse events such as withdrawal symptoms at discontinuation, onset of tolerance and resistance phenomena and switch and cycle acceleration in bipolar patients. Unfavorable long-term outcomes and paradoxical effects (depression inducing and symptomatic worsening) have also been reported. All these phenomena may be explained on the basis of the oppositional model of tolerance. Continued drug treatment may recruit processes that oppose the initial acute effect of a drug. When drug treatment ends, these processes may operate unopposed, at least for some time and increase vulnerability to relapse. Antidepressant drugs are crucial in the treatment of major depressive episodes. However, appraisal and testing of the oppositional model of tolerance may yield important insights as to long-term treatment and achievement of enduring effects.

Abrupt Discontinuation of Psychotropic Drugs Following Confirmation of Pregnancy: A Risky Practice

A number of pregnant women suffer from psychiatric disorders that require treatment with psychotropic drugs. A literature review suggests that these medications are relatively safe to use during pregnancy. Abrupt discontinuation of these drugs can have both physiological and psychological ramifications, which include unpleasant physical symptoms and re-emergence of the psychiatric condition. Therefore, it is not good practice to discontinue these medications abruptly upon diagnosis of pregnancy.

Delirium: an important (but often unrecognized) clinical syndrome

Delirium is a clinical syndrome characterized by the acute onset of a disturbance in consciousness accompanied by a reduced ability to focus, sustain, or shift attention. It may foreshadow impending death in as many as 25% of hospitalized inpatients and may be a source of significant morbidity in those who present with this syndrome. The disorder may go unrecognized by hospital staff as well as those close to an affected individual, and this oversight may lead to poorer outcomes including longer lengths of stay in acute care hospitals, the need for nursing home placement, prolonged cognitive disturbances, and protracted disability. This paper will address this complex condition, focusing on its history, definition, epidemiology, pathophysiology, recognition, risk factors, and clinical quantification. Its prevention and treatment will be covered elsewhere in this journal.

Steps Following Attainment of Remission: Discontinuation of Antidepressant Therapy

Depressive disorders require long-term treatment with antidepressants, psychotherapy, or both. The goal of antidepressant therapy is complete remission of symptoms and return to normal daily functioning. Studies have shown that achieving remission and continuing antidepressant therapy long after the acute symptoms remit can protect against the relapse or recurrence of the psychiatric episode. Many patients, however, inadvertently or intentionally skip doses of their antidepressant, and even discontinue it, if their symptoms improve or if they experience side effects. Antidepressant discontinuation may increase the risk of relapse or precipitate certain distressing symptoms such as gastrointestinal complaints, dizziness, flu-like symptoms, equilibrium disturbances, and sleep disorders. Documented with all classes of antidepressants, these reactions may emerge within a couple of days, or even hours, after the abrupt discontinuation of an antidepressant with a short half-life. These distressing responses may be mistaken for a relapse or recurrence. It is important to recognize the potential for these sequelae and educate patients about the need to take all antidepressants at the doses prescribed, warning them of the symptoms that may occur if they skip doses or stop their medication too quickly. Antidepressants should be tapered slowly over a period of days, weeks, or even months, depending on the dose, duration of treatment, and pharmacologic properties of the agent, as well as the patient's individual response. This article reviews the risks and reactions associated with discontinuation of antidepressants. It offers guidelines for distinguishing relapse and recurrence from discontinuation responses as well as for prevention and management of the antidepressant discontinuation syndrome.

Neuroleptic discontinuation syndromes

The existence of discontinuation syndromes following treatment with neuroleptic (antipsychotic) drugs was first outlined in the mid-1960s but the effects of such syndromes have been neglected since then. We have pursued evidence for the existence and nature of discontinuation syndromes following neuroleptics through reports of difficulties following the use of dopamine blocking anti-emetics, the use of chlorpromazine to treat tuberculosis, the use of antidepressant-neuroleptic combinations in affective disorders, the occurrence of tardive syndromes and studies designed to establish the existence of discontinuation syndromes in schizophrenia. Combined these bodies of data point strongly to the existence of discontinuation syndromes after cessation of treatment with neuroleptics which may involve features other than motor dyskinesias. There is at present little evidence on the relative frequency of such syndromes or predisposing factors. The area needs research input to establish the nature of the syndromes that may result, their frequency, predisposing factors and best methods of treatment.

Restlessness: the anatomy of a neuropsychiatric symptom

OBJECTIVE

The aim of this paper is to review the literature on restlessness and related syndromes in order to examine the different causes and clinical descriptions, and to present a pathogenetic model that would incorporate its diverse aetiology.

METHOD

A literature search was undertaken with restlessness, agitation, akathisia, hyperactivity, fidgetiness and jitteriness as key words.

RESULTS

Causes of restlessness are diverse, and its distinction from other descriptions, such as agitation and hyperactivity, is poorly defined in the literature. Detailed descriptions of the syndromes are therefore lacking. The neuroanatomical basis of restlessness may consist of abnormalities in the cortico-subcortical neuronal circuits, the complex regulation of which may explain why different causes often lead to a common end result.

CONCLUSIONS

The terms used to describe restlessness and related disorders should be standardised, and the clinical manifestations investigated pedantically. Human and animal studies should investigate the pathophysiology so that intervention can be based on the underlying mechanisms.

Effect of repeated haloperidol administration on phencyclidine discrimination in rats

1. Previous research has shown that acute doses of haloperidol block many of themotor stimulatory effects of phencyclidine (PCP) and other PCP-like drugs. In addition, when given acutely, haloperidol produces partial attenuation of PCP's discriminative stimulus effects in rats. 2. Haloperidol is often administered chronically in clinical situations; hence, it is important to investigate the effects of repeated, as well as acute, dosing with this drug. 3. The purpose of the present study was to examine the effects of repeated administration of haloperidol on PCP discrimination in rats. Rats were trained to discriminate PCP (2.0 mg/kg) from saline in a two-lever drug discrimination procedure and were tested with cumulative doses of PCP before and after repeated administration of saline and of haloperidol (0.5 mg/kg/day). 4. Discrimination training was suspended during the two 14-15-day repeated dosing regimens. Suspended training with repeated saline administration had little effect on the dose-effect curve for % PCP-lever responding. 5. Repeated administration of haloperidol produced some diminution of PCP discrimination. After haloperidol, the ED50 for % PCP-lever responding was 1.4 mg/kg, compared to the pre-haloperidol ED50 of 0.7 mg/kg. 6. These results are consistent with those of acute dosing studies with haloperidol in PCP-trained rats and suggest that repeated administration of haloperidol may disrupt PCP's discriminative stimulus effects, although most rats were still able to discriminate the higher doses of PCP.

Nicotine withdrawal versus other drug withdrawal syndromes: similarities and dissimilarities

Many of the symptoms of nicotine withdrawal are similar to those of other drug withdrawal syndromes: anxiety, awakening during sleep, depression, difficulty concentrating, impatience, irritability/anger and restlessness. Slowing of the heart rate and weight gain are distinguishing features of tobacco withdrawal. Although nicotine withdrawal may not produce medical consequences, it lasts for several weeks and can be severe in some smokers. Like most other drug withdrawals, nicotine withdrawal is time-limited, occurs in non-humans, is influenced by instructions/expectancy and abates with replacement therapy and gradual reduction. Unlike some other drug withdrawal syndromes, protracted, neonatal or precipitated withdrawal does not occur. Whether nicotine withdrawal is associated with tolerance, acute physical dependence, greater duration and intensity of use, rapid reinstatement, symptom stages, cross-dependence with other nicotine ligands, reduction by non-pharmacological interventions and genetic influences is unclear. Whether nicotine withdrawal plays a major role in relapse to smoking has not been established but this is also true for other drug withdrawal syndromes.

Haloperidol Concentrations in Patients With Alzheimer's Dementia

To investigate the relationship between clinical response and haloperidol blood concentrations in Alzheimer's dementia (AD) patients with behavior problems, 29 AD inpatients were assigned to a fixed oral dosage of haloperidol (0.5 mg, 1.0 mg, or 2.0 mg) every 12 hours for 3 weeks. BEHAVE-AD ratings and concentrations of plasma and RBC haloperidol and reduced haloperidol were obtained on Days 8, 15, and 22. Although no significant linear or curvilinear relationships were apparent between percent of change on BEHAVE-AD and plasma or RBC haloperidol concentrations, a good response (change ≥ 30%) was observed in 55% of the patients who entered the study.