Desipramine toxicity

Ashton AK. Lack of desipramine toxicity with citalopram. J Clin Psychiatry 2000 61(2) 144. 

The raised desipramine levels are thought to result from decreased metabolism and clearance, caused by propafenone. The general importance of this case is uncertain, but be alert for signs of desipramine toxicity in any patient given propafenone concurrently. Adjust the desipramine dosage appropriately. 

Treatment with imipramine, the most studied TCA, leaves 45% to 70% of patients panic free. Both desipramine and clomipramine have demonstrated effectiveness in PD as well. Despite their efficacy, TCAs are considered second- or third-line pharmacotherapy due to poorer tolerability and toxicity on overdose.48,49 TCAs are associated with a greater rate of discontinuation from treatment than SSRIs.53 PD patients taking TCAs may experience anticholinergic effects, orthostatic hypotension, sweating, sleep disturbances, dizziness, fatigue, sexual dysfunction, and weight gain. Stimulant-like side effects occur in up to 40% of patients.49... 

Rao et al.20 demonstrated a fluorescence polarization immunoassay for evaluating serum concentrations of tricyclic antidepressants (amitriptyline, imipramine, clomipramine, and doxepin) with respect to nonresponse, compliance, therapeutic window, and influences of age, sex, substance abuse, and toxicity. Abbott Laboratories TDx/TDxFLx Toxicology Tricyclic Assay FPIA (fluorescence polarization immunoassay) was used. This assay of 50 /uL samples contained tricyclic antidepressant antibodies raised in rabbits and fluorescein-labeled tricyclic antidepressant as a tracer. The assay was calibrated with imipramine in the range of 75 to 1000 fig/L (268 to 3571 nmol/L). Intra-assay and inter-assay coefficients of variation for internal quality control samples from the manufacturer were 4.2 and 4.7%, respectively. The limits of detection were 72,71,64, and 72 nmol/L for amitriptyline, imipramine, clomipramine, and doxepin, respectively. This high-throughput immunoassay was easy to use although amitriptyline, dosulepine, desipramine, and nortriptyline showed cross-reactivities ranging from 74 to 100%. 

Additional ADRs linked to diet pills include psychosis myocardial ischemia drug interactions, such as the interaction of fenfluramine with imipramine, fenfluramine with amitriptyline or desipramine, or the toxic reaction between fluoxetine and phentermine and the release of serotonin while inhibiting its reuptake, contributing to hyperserotonin reactions. When the next craze takes hold of patients and their physicians, hopefully physicians and pharmacists will take a more vocal position and recommend restraint, xmtil some proof of efficacy and lack of toxicity is shown for new faddish off-label combinations. 

Tricyclic Antidepressants (TCAs). Because of their effectiveness not only for depression but for anxiety disorders such as panic disorder as well, TCAs were the first medications formally tested in the treatment of PTSD. Three TCAs, amitriptyline, imipramine, and desipramine, have been studied in small trials, producing modest benefit for reexperiencing and hyperarousal symptoms, without any relief of avoidance/numbing symptoms. Given this limited benefit in conjunction with the side effect burden and potential for toxicity in a suicide prone population, TCAs are infrequently used in the treatment of PTSD. Please refer to Chapter 3 for more information regarding TCAs. 

Determination of desipramine plasma concentrations is not routinely recommended but may be useful in identifying toxicity drug interactions, or noncompliance (adjustments in dosage should be made according to clinical response, not plasma concentrations) therapeutic level is 50-200 ng/ml... 

For some psychotropic drugs (e.g., lithium and some antidepressants) a good correlation exists between plasma levels and therapeutic or toxic effects. Optimum steady-state levels can now be predicted from single-dose blood level data of some drugs (lithium, nortriptyline, desipramine). Altered PK behavior in children has to be taken into consideration in using psychotropic drugs. With development of suitable drug... 

Chuang DM, Gao X-M, Paul SM N-methyl-D-aspartate exposure blocks glutamate toxicity in cultured cerebellar granule cells. Mol Pharmacol 42 210-216, 1992 Chugh Y, Saha N, Sankaranarayanan A, et al Enhancement of memory retrieval and attenuation of scopolamine-induced amnesia following administration of S-HTj antagonist ICS 205-930. Pharmacol Toxicol 69 105-106, 1991 Ciraulo DA, Jaffe JH Tricyclic antidepressants in the treatment of depression associated with alcoholism. Clin Psychopharmacol 1 146, 1981 Ciraulo DA, Barnhill JG, Jaffe JH Clinical pharmacokinetics of imipramine and desipramine in alcoholics and normal volunteers. Pharmacol Ther 43 539-548, 1988... 

As with most data for reboxetine, this information primarily comes from summary papers rather than primary sources (473, 474). With this caveat, the adverse-effect profile of reboxetine is consistent with its pharmacology as an NSRI. Thus, it is similar to that of desipramine and maprotiline but without the risk of serious CNS (i.e., seizures, delirium) or cardiac (i.e., conduction disturbances) toxicity. The most common adverse effects of reboxetine are dry mouth, constipation, urinary hesitancy, increased sweating, insomnia, tachycardia, and vertigo. Whereas the first three adverse effects are commonly called anticholinergic, they are well known to occur with sympathomimetic drugs as well. In other words, these effects can be either the result of decreased cholinergic tone or increased sympathetic tone, although they tend to be more severe with the former than the latter. In contrast to TCAs, reboxetine does not directly interfere with intracardiac conduction. The tachycardia produced by reboxetine, however, can be associated with occasional atrial or ventricular ectopic beats in elderly patients. 

The adverse effects of TCAs are also similar to those reported in adults (see Chapter 7). The secondary amine TCAs (e.g., desipramine, nortriptyline) are generally as well tolerated as newer antidepressants. Increased blood pressure may be more likely to occur in children than in adults but hypertension per se is rare ( 135). The most common cardiovascular effect is mild tachycardia. Despite their generally favorable adverse effect profile, secondary amine TCAs can cause serious toxicity in children and adolescents just as in adults when a taken in an overdose or when a high TCA plasma level occurs as a result of slow metabolism ( 136). For that reason, most clinicians reserve TCAs for the child or adolescent who has at least a moderate depressive disorder unresponsive to a trial of one or more newer antidepressants. In such instances, TDM should be done at least once to ensure plasma concentrations greater than 450 ng/mL do not develop ( 137). Such levels are associated with an increased risk of the following ... 

The secondary amine TCAs, including desipramine and nortriptyline, lack active metabolites and have fairly linear kinetics. These TCAs have a wide therapeutic window, and serum levels are reliable in predicting response and toxicity. 

It has been used successfully in combination with the tricyclic antidepressant desipramine in a 45-year-old woman who had previously suffered tricyclic toxicity when desipramine had been combined with paroxetine (30). 

MAOIs TCAs-AMITRIPTYLINE CLOMIPRAMINE DESIPRAMINE IMIPRAMINE NORTRIPTYLINE t risk of stroke, hyperpyrexia and convulsions, t plasma concentrations of TCAs, with risk of toxic effects, t risk of serotonin syndrome and of adrenergic syndrome with older MAOIs. Clomipramine may trigger acute confusion in Parkinson s disease when used with selegiline TCAs are believed to also act by inhibiting the reuptake of serotonin and norepinephrine, increasing the risk of serotonin and adrenergic syndromes. The combination of TCAs and antidepressants can t risk of seizures Very hazardous interaction. Avoid concurrent use and consider the use of an alternative antidepressant. Be aware that seizures occur with overdose of TCAs just before cardiac arrest... 

TCAs DRUG DEPENDENCE THERAPIES-BUPROPION 1. t risk of seizures This risk is marked in elderly people, in patients with a history of seizures, addiction to opiates/cocaine/ stimulants, and in diabetics treated with oral hypoglycaemics or insulin 2. t plasma concentrations of amitriptyline, clomipramine, desipramine, doxepin and imipramine, with risk of toxic effects 1. Bupropion is associated with a dose-related risk of seizures. TCAs lower the seizure threshold. Additive effects when combined 2. Bupropion and its metabolite hydroxybupropion inhibit CYP2D6 1. Extreme caution. The dose of bupropion should not exceed 450 mg/day (or 150 mg/day in those with severe hepatic cirrhosis) 2. Initiate therapy of these drugs at the lowest effective dose... 

CINACALCET BUPROPION T plasma concentrations of these substrates, with risk of toxic effects Bupropion and its metabolite hydroxybupropion inhibit CYP2D6 Initiate therapy of these drugs, particularly those with a narrow therapeutic index, at the lowest effective dose. Interaction is likely to be important with substrates for which CYP2D6 is considered the only metabolic pathway (e.g. hydrocodone, oxycodone, desipramine, paroxetine, chlorpheniramine, mesoridazine, alprenolol, amphetamines, atomoxetine)... 

Toxicity. In adults the estimated minimum lethal dose is 1 g, although fatalities have occurred with less and patients have survived the ingestion of as much as 5 g. In children, as little as 350 mg may be fatal. Blood concentrations greater than 0.5 jj-g/ml (imipramine and desipramine) may cause toxic effects and imipramine concentrations of 0.8 to 4.5 to 13 pg/ml have been associated with fatalities. 

Medications play an important part in the treatment of ADD. Stimulants are the mainstay of the treatment of ADD methylphenidate (Ritalin), dextroamphetamine (Dexedrine), and pemoline (Cylert). These differ in their half-lives, with Ritalin having the shortest and Cylert the longest. A warning has recently been issued about Cylert because of reports of sometimes fatal liver toxicity. Thus, it is recommended that it be used only if methylphenidate and dextroamphetamine are ineffective. There is individual variability in resporise, so that a person who does not respond to one may respond well to another. Other medications can also be effective in the treatment of ADD and may be useful, especially in residual ADD, where substance abuse may be an issue. These include tricyclic antidepressants (especially desipramine and imi-pramine) SSRIs, bupropion, venlafaxine, and clonidine. There are reports of antipsy-chotics and lithium being helpful in selected cases, as well. 

Psychiatric patients often take multiple psychotropic medications and have medical illnesses that require additional pharmacother-apeutic treatments. Psychiatric practitioners must recognize that administration of multiple medications can alter pharmacokinetic profiles of compounds that are biotransformed by the CYP enzymes. For example, the addition of the popular selective serotonin reuptake inhibitor (SSRI) fluoxetine to a treatment regimen for depression that includes the TCA desipramine has been reported to produce toxic levels of the TCA because of competi-... 

---