Desipramine dosing

Tricyclic antidepressants (TCAs) such as amitriptyline and doxepin have been used with some success in the treatment of IBS-related pain (Table 18-5). They modulate pain principally through their effect on neurotransmitter reuptake, especially norepinephrine and serotonin. Their helpfulness in functional gastrointestinal disorders seems independent of mood-altering effects normally associated with these agents. Low-dose TCAs (e.g., amitriptyline, desipramine, or doxepin 10 to 25 mg daily) may help patients with IBS who predominantly experience diarrhea or pain. 

Desipramine has been used to facilitate withdrawal from chronic PCP use. The rationale is that PCP depletes norepinephrine concentrations in brain, and that this tricyclic antidepressant is the most selective blocker of norepinephrine uptake. Consequently, some of the deficiency of the neurotransmitter could be remedied. A dose of 25 to 50 mg was said to reduce craving for several hours. Six of eight patients treated with this drug were successfully withdrawn, while none of the eight offered other types of programs were successful (45). 

In 1985, 1 finally took the county public health psychiatrist s recommendation to try Desipramine, an ostensibly mild tricyclic antidepressant. I took tiny dot doses, and for a month or so I felt encouraged except for intense muscle tension and clenching. The psychiatrist said it was not remotely possible that this response was related to the medication. I took a low dose for four more months before throwing them out. The side effects had escalated horribly, and become what I later learned are called tardive dyskinesia and tardive dystonia. Subsequently, chemical and electromagnetic field exposures, feeling compromised or ashamed, or stress can trigger uncontrollable movement, hyperactivity, rigid posture and then, frequently, paralysis. 

Vascular effects Cocaine causes increases in blood pressure and heart rate, which fall to normal levels between doses (Foltin et al. 1995). Tachyphylaxis develops to the cardiovascular effects, even within a single session. Concurrent use of ethanol, cannabis, and cocaine causes even greater cardiovascular effects than those of each drug alone. Interactions can also occur with antidepressant drugs like desipramine. 

The common side effects of TCAs frequently limit their usefulness, particularly in older patients. Side effects can be minimized by starting at low doses that are slowly titrated upward or by choosing one of the so-called secondary amine TCAs, nortriptyline and desipramine, with less potent side effects. In addition, it should be remembered that some of the troublesome side effects, such as sedation, tend to disappear over time. 

Tricyclic Antidepressants (TCAs). The TCAs, particularly imipramine (Tofranil), were also discovered soon after their introduction to be effective in the treatment of panic attacks. Imipramine, the best-studied TCA in the treatment of panic disorder, is most often helpful at daily doses of 150-250 mg, though it must be started at 10-25 mg, usually at bedtime, and gradually increased over 2-4 weeks. Although they are not as well studied, many clinicians prefer to use the secondary amine TCAs, desipramine (Norpramin) and nortriptyline (Pamelor), because they have milder side effects than imipramine. Clomipramine (Anafranil), though probably the TCA with the greatest side effect burden, is often said to be most effective in patients with refractory disease. 

Tricyclic Antidepressants (TCAs). The TCAs have been nsed to treat ADHD for 30 or more years. Most often used are imipramine (Tofranil) and desipramine (Norpramin), mainly becanse they are the TCAs that most specihcally increase norepinephrine activity. Remember, boosting norepinephrine activity in the brain shonld improve attention. Other TCAs, namely, amitriptyline (Elavil, Endep) and nortriptyline (Pamelor), have been used, though they also increase norepinephrine activity. TCAs do offer a modest benefit for both the inattention and the hyperactivity of ADHD. In addition, they are often effective at doses mnch lower than those required to treat depression. However, their effectiveness nsnally falls short of the stimulant medications. In addition, TCAs have considerable side effects including dry mouth, constipation, drowsiness, weight gain, and adverse cardiac effects. 

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... 

Biederman et al. (1989a,b) also found desipramine (at the relatively high mean dose of 4.6 mg/kg/day) to be safe and effective for treatment of ADD. Despite these positive results, however, concerns about prolonged cardiac conduction times and the reports of several sudden deaths of children on desipramine have left many clinicians and parents reluctant to use the drug (Riddle, et ah, 1993). Another less well-studied tricyclic, nortriptyline, which some believe to have less potential cardiotoxicity, has shown promise in a retrospective study in children with ADHD plus tic disorder (Spencer et al., 1993b). 

Lydiard RB Desipramine in agoraphobia with panic attacks an open, fixed-dose study. J Clin Psychopharmacol 7 258-260, 1987... 

Imipramine, amitriptyline, doxepin, desipramine, clomipramine, and trimipramine therapy can be initiated at 25-50 mg/day. Divided dosing may be used at first to minimize side effects, but eventually the entire dose can be given at bedtime. The dose can be increased to 150 mg/day the second week, 225 mg/day the third week, and 300 mg/ day the fourth week. The dose of clomipramine should not exceed 250 mg/day because of an increased risk of seizures at higher doses. 

Clinically meaningful plasma levels are available for imipramine, desipramine, and nortriptyline. For imipramine, the sum of the plasma levels of imipramine and the desmethyl metabolite (desipramine) should be greater than 200-250 ng/mL. Desipramine levels should be greater than 125 ng/mL. A therapeutic window has been noted for nortriptyline, with optimal response between 50 and 150 ng/mL. These therapeutic levels are based on steady-state concentrations, which are reached after 5-7 days of administration of these medications. Blood should be drawn approximately 10-14 hours after the last dose of medication. 

A dose-related risk of seizures has been found with clomipramine, which has led to the recommendation that the total daily dose of this drug not exceed 250 mg. Overdoses of TCAs, particularly amoxa-pine and desipramine, are associated with seizures. Whether therapeutic doses of TCAs lower the seizure threshold is controversial. Nonetheless, other classes may be safer options for individuals with epilepsy. 

HCA is the term is used to refer to both TCAs and analogues of these agents, such as maprotiline and amoxapine. TCAs are by far the most commonly used HCAs and include tertiary amines such as amitriptyline, doxepin, and imipramine and secondary amines such as desipramine and nortriptyline. Most secondary amines could also be viewed as NE-selective antidepressants, while the hallmark of tertiary amine TCAs is their effects on multiple neurotransmitters over their clinically relevant dosing range. 

As a results of these studies, clinicians have proposed that switching to reboxetine or bupropion might a useful strategy given that these antidepressants share the ability with desipramine and imipramine to block NE uptake. Nevertheless, only one small open label study has been done to test this possibility ( 365). If bupropion is to be used in patients switched from an ineffective trial of fluoxetine, the dose should be kept low for several weeks to allow for the clearance of fluoxetine and norfluoxetine. Case reports indicate that fluoxetine can elevate levels of the active metabolites of bupropion, which, in turn, could mediate an increase risk of adverse effects (366). 

Because reboxetine and bupropion share with desipramine the ability to block the NE uptake pump, some clinician may want to combine them with an SSRI. Bupropion, however, should be used cautiously with fluvoxamine, fluoxetine, and paroxetine because these three antidepressants inhibit one or more CYP enzymes to a substantial degree at their lowest, usually effective antidepressant dose. Therefore, the dose of bupropion should be kept low and TDM could be used to ensure that unusually high levels of bupropion or its active metabolites do not develop. 

This antidepressant can interact with other drugs via its two mechanisms of action serotonin and NE uptake inhibition. The former action means that the same pharmacodynamic interactions will occur with venlafaxine as with SSRIs, including the serotonin syndrome. At higher doses, venlafaxine is also prone to the same pharmacodynamic interactions as NSRIs such as secondary amine TCAs like desipramine and with newer NSRIs such reboxetine. Thus, the combination of high-dose venlafaxine plus an MAOl could produce a hypertensive crisis as well as the serotonin syndrome. 

Like alprazolam, clonazepam may cause treatment-emergent depression in some patients. Pollack et al. (42) also reported that only 10% of their patients who remained on clonazepam had a history of depression, although 47% lost to follow-up and 30% who eventually required alternate treatment had histories of dysthymia or depression. Of 31 patients without a prior history of affective illness, depression developed in three on low daily dosages (0.75, 1.5, and 2 mg), one was switched to alprazolam, and the others responded to the addition of desipramine or imipramine. These investigators recommend that, until further data are available, PD patients with chronic or concurrent depression should not be given clonazepam alone and that those in whom depression develops during clonazepam therapy should have their dose lowered or an adjunctive antidepressant added. 

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