Venlafaxine and

Droperidol, metoclopramide, prochlorperazine, promethazine, venlafaxine, and reserpine... 

These types of antidepressant were introduced around 10 years after the SSRIs. They include the serotonin noradrenaline reuptake inhibitor venlafaxine and the selective noradrenaline reuptake inhibitor reboxetine. Although there are fewer data about these drugs, clinical experience has shown they are well tolerated and, unlike the SSRIs, they are only weak inhibitors of drug metabolism (Kent, 2000). Depression is a common psychiatric disorder seen in the elderly and often remains untreated or inadequately treated (Forsell and Fastbom, 2000). Venlafaxine was shown to improve the mood in a group of 36 older patients without any effect on cognitive function, an important consideration where there is the possibility of the coexistence of mild or undiagnosed dementia (Tsolaki et al., 2000). 

The serotonin-norepinephrine reuptake inhibitors include venlafaxine and duloxetine. Venlafaxine is an inhibitor of 5-HT and NE reuptake and a weak inhibitor of DA reuptake. Desvenlafaxine (Pristiq) was recently approved by the FDA. The dose is 50 mg once daily. 

There are three approved drugs, venlafaxine (16), duloxetine (17) and milnacipran (18), in the serotonin-norepinephrine reuptake inhibitor (SNRI) class. Whereas milnacipran blocks 5-HT and NE reuptake with almost equal potency, venlafaxine and duloxetine block 5-HT reuptake preferentially [39-41]. Clinical evidence shows that SNRIs have comparable efficacy in the treatment of MDD compared with antidepressants in the SSRI class. An advantage with SNRIs appears to be the ability of alleviating chronic pain associated with, and independent of depression [42-44],... 

Duverneuil and coworkers (2003) have developed a method for the determination of 11 of the most commonly prescribed non-tricyclic antidepressants and some of their metabolites these include paroxetine, fluoxetine, norfluoxetine, sertraline, citalopram, fluvoxamine mirtazapine, venlafaxine, and 0-des-methylvenlafaxine. The method involves an LLE procedure followed by an HPLC separation with photodiode-array UV detection at three different wavelengths (220, 240, and 290 nm). The total run time was 18 min. The extraction recoveries were calculated to be in the range of 74-109% and the lower limit of detection (LLOD) reported was 2.5-5 ng/ml. A method published by Tournel and associates (2001) also reported the simultaneous determination of several newer antidepressants by RP-HPLC with UV detection. The compounds were isolated from human serum using an LLE process. The LLOQ ranged from 15-50 ng/ml depending on the analyte of interest. The total run time for all compounds eluted was approximately 20 min. 

Cherkaoui, S., Rudaz, S., and Veuthey, J. L. (2001). Nonaqueous capillary electrophoresis-mass spectrometry for separation of venlafaxine and its phase I metabolites. Electrophoresis 22, 491 —496. 

The traditional scheme is complicated by the fact that some antidepressants exhibit characteristics of more than one class. For example, clomipramine, a tricyclic antidepressant (TCA) with side effects and toxicity similar to other TCAs, works more like the selective serotonin reuptake inhibitors (SSRls). Similarly, venlafaxine and duloxetine, which are usually grouped with the atypical antidepressants, have a side effect and safety profile comparable to the SSRls. Although a classihcation system based on mechanism of action offers some advantage (see Table 3.7), even this scheme is limited by the fact that antidepressants that work in the same way may have widely divergent side effect and safety profiles. In the following discussion, the traditional classification system is adopted. Although fraught with problems and inconsistencies. 

When starting a SSRI, the abrupt increase in serotonin may cause side effects. In the brain, the short-term effects include headache, sleep disturbance, nervousness, anxiety, and tremulousness. The digestive system effects include nausea, loose stools, decreased appetite, and indigestion. Most of these effects are mild and shortlived or can be managed with over-the-counter remedies. Nausea, for example, can be minimized by taking a SSRI after meals. These effects are also commonly seen with venlafaxine and duloxetine, atypical antidepressants that block serotonin reuptake like the SSRIs. 

Duloxetine (Cymbalta). Duloxetine, the newest of the antidepressants approved in the United States, like venlafaxine and most TCAs, acts by blocking both serotonin... 

In addition, whenever an antidepressant that blocks serotonin reuptake is discontinued, an unpleasant but harmless discontinuation syndrome manifested by abdominal discomfort, instability, anxiety, and occasionally painful shock-like sensations in the extremities can arise. The risk appears to be greatest with venlafaxine and paroxetine. Consequently, switching from one of these medications to another that does not block serotonin reuptake requires a gradual taper of the first medication over days to weeks. 

Atypical Antidepressants. Preliminary open label studies suggested that ven-lafaxine and trazodone might be effective for OCD. However, controlled studies have not yet been completed for venlafaxine, and a controlled study of trazodone (100-200 mg/day) did not find it an effective treatment for OCD. 

The so-called atypical antidepressants such as venlafaxine and bupropion can be tried, but their safety and efficacy in treating patients with dementia have not been well studied. The older tricyclic antidepressants and monoamine oxidase inhibitors are not tolerated well by demented patients and should be avoided. Two possible exceptions are nortriptyline (Pamelor) and desipramine (Norpramin), but even these should be tried only after the newer antidepressants have proved ineffective. 

Figure 7.3. Structural formulae of the noradrenaline (norepinephrine)/dopamine reuptake inhibitor amfebutamone (bupropion) and some nonselective noradrenaline and serotonin (5-hydroxytr3 tamine 5-HT) reuptake inhibitors (venlafaxine, and...

Lorazepam is a short-acting benzodiazepine indicated for use in relieving anxiety and insomnia. Lorazepam may also be administered perioperatively to alleviate pain and in status epilepticus. Imipramine is a tricyclic antidepressant, paroxetine is a selective serotonin re-uptake inhibitor, venlafaxine is a serotonin and adrenaline re-uptake inhibitor and moclobemide is a reversible monoamine oxidase inhibitor. Imipramine, paroxetine, venlafaxine and moclobemide are all classified as antidepressants. 

Pharmacology Venlafaxine and its active metabolite, 0-desmethylvenlafaxine (ODV), are potent inhibitors of neuronal serotonin and norepinephrine reuptake and weak inhibitors of dopamine reuptake. 

Pharmacokinetics Venlafaxine is well absorbed (at least 92%) and extensively metabolized in the liver. ODV is the only major active metabolite. Renal elimination of venlafaxine and its metabolites is the primary route of excretion. Venlafaxine ER provides a slower rate of absorption but the same extent of absorption compared with the immediate-release tablet. 

Lactation Venlafaxine and ODV are excreted in breast milk. Children Safety and efficacy have not been established. 

Venlafaxine is metabolized to its active metabolite, ODV, by cytochrome P-450 2D6. Therefore, the potential exists for a drug interaction between venlafaxine and drugs that inhibit this isoenzyme. 

Side effects, mainly due to serotonin reuptake inhibition include G1 upset, nervousness, and sexual dysfunction. SSRls are associated with an increased risk of falls. Hyponatraemia due to SIADH is an uncommon, but important side effect in elderly patients. Selective serotonin and norepinephrine reuptake inhibitors (S SNRls) such as venlafaxine and duloxetine are also useful in older patients. Other heterocyclic antidepressants of importance in older patients because of relative safety include bupro-prion and mirtazepine. They are reserved for patients with resistance to or intolerance of SSRls. Currently, trazodone is used mostly for sleep disturbance in depression in doses of 50-100 mg at bedtime. The monoamine oxidase inhibitors phenelzine. 

Taken together, the efficacy of antidepressants covers the spectrum of anxiety disorders, although there are important differences between drugs in the group (Table 3). Several new antidepressants have been marketed since the SS-RIs venlafaxine and mirtazapine are discussed later (Sects. 3.2.1.2 and 3.2.1.4) nefazodone, a serotonin reuptake inhibitor and postsynaptic 5-HT2 blocker showed promise in early studies but was recently withdrawn by its manufacturers reboxetine, a noradrenaline reuptake inhibitor (NARI) showed benefits in panic disorder in one published study (Versiani et al. 2002) and further evidence of its anxiolytic efficacy is awaited. 

Venlafaxine (Effexor) inhibits the reuptake of both serotonin and norepinephrine at their respective presy-naptic sites. This drug does not have significant effects at muscarinic, histamine, or a-adrenergic receptors and therefore is devoid of many of the side effects associated with the TCAs. Venlafaxine and its active metabo-... 

C. Nortriptyline (Pamelor) is a TCA, and as a class these drugs require at least one steady-state blood level to safely and effectively use the medication. Paroxetine, venlafaxine, and bupropion have not had blood levels correlated to response, and their relatively low toxicity does not require therapeutic blood monitoring. Nardil is a MAOI, which can be... 

Goldberg R. Antidepressant use in the elderly. Current status of nefazodone, venlafaxine and moclobemide. Drugs Aging 1997,11 119-131. 

The coadministration of venlafaxine and MAOls is contraindicated because of the risk of serotonin syndrome. Venlafaxine is a relatively weak inhibitor of the CYP450-2D6 system, therefore it has few drug interactions (Ball et al. 1997). 

W.J., and Chiang, S.T. (1992) Introduction of a composite parameter to the pharmacokinetics of venlafaxine and its active O-desmethyl metabolite. / Clin Pharmacol 32 716-724. 

Most child and adolescent studies published thus far have focused on the effects of the tricyclic antidepressants (TCAs) and, more recently, the SSRIs. A few open studies have also shown that monoamine oxidase inhibitors (MAOIs) can be used safely with children and adolescents (Ryan et ah, 1988b), but noncompliance with dietary requirements may present a significant problem for minors. Other antidepressants, including the heterocyclics (HTC) (e.g., amoxapine, maprotiline), buproprion, venlafaxine, and nefazodone, have been found to be efficacious for the treatment of depressed adults (APA, 2000), but they have not been well studied for the treatment of MDD in children and adolescents. Therefore, this chapter mainly describes the use of SSRIs and TCAs for youth with MDD. 

Poirier, M.F. and Boyer, P. (1999) Venlafaxine and paroxetine in treatment-resistant depression double-blind, randomized comparison. Br J Psychiatry 175 12-16. 

A more common approach in difficult to treat cases would be the combination of clomipramine with a SSRI several reports lend support to this practice (Simeon and Thatte, 1990 Figueroa et al., 1998). In this situation, careful attention to the potential pharmacokinetic interactions discussed above are recommended. Sertraline and citalopram are least likely to elevate tricyclic levels due to less potential GYP interactions. By expert consensus, second- (venlafaxine) and third-line (nefazadone and gabapentin) agents may be used when clinical response is inadequate despite a lack of controlled data. Venlafaxine may be substituted for a more typical SSRI while nefazadone or gabapentin may be added to either clomipramine or a SSRI. The combination of venlafaxine with other SSRIs is not generally recommended as it may increase the risk of a serotonin syndrome. The addition of nefazadone to SSRIs presents a lesser risk. 

Other alternatives to the stimulants that have been studied for treatment of ADHD in children and adults include the tricyclic antidepressants desipramine and nortriptyline the newer antidepressants bupropion, venlafaxine, and atomoxetine the beta-blocker pindolol and the selective monoamine oxidase inhibitor, deprenyl. Across these agents, the number of controlled studies varies from none (nortriptyline) to four (bupropion). Only deprenyl and desipramine have been studied in children with ADHD and tic disorders. 

In cases of SSRI nonresponse, consideration should be given to using venlafaxine and nefazadone, as these agents appear to be safe and have consensus support for their use. Table 43.2 provides further detailed guidelines in matching specific pharmacological agents with PTSD symptom clusters. 

In the Zito et al. study (2000), antidepressants were the second most commonly prescribed psychotropic medication. There are a total of 10 studies or case reports in the literature examining antidepressant use in preschool children (Table 49.4). None of the 10 studies are randomized, double-blind, or placebo-controlled trials. The ten uncontrolled studies looked at a total of 37 preschool children. Six of the studies looked at a total of 29 preschoolers with autism or childhood schizophrenia (Campbell et ah, 1971a Petti and Campbell, 1975 Holttum et ah, 1994 Sanchez et ah, 1996 DeLong et ah, 1998 Hollander et ah, 2000). While these six studies are difficult to compare, given the small sample sizes and the different treatment medications, these open-label studies suggest that clomipramine, venlafaxine, and fluoxetine may be helpful to reduce some psychiatric symptoms found in autistic... 

Venlafaxine and milnacipran are two members of a new class of antidepressants that have selective effects on the reuptake of both serotonin and noradrenaline—serotonin noradrenaline reuptake inhibitors (SNRIs). In theory, based on the findings of B. M. Baron and colleagues [1988 and of J. C. Nelson and colleagues (1991), the combination of these two pharmacological actions should be associated with superior efficacy either in terms of rapid onset of action or extra efficacy at the end of treatment. 

In contrast, a less extensive but still convincing database has identified important clinical differences in efficacy for antidepressants used to treat patients with atypical or comorbid depression. Individuals with atypical depression (distinct quality of mood, hyperphagia, hypersomnia, psychomotor retardation, rejection sensitivity, and such unusual atypical features as chocolate craving] have superior responses to monoamine oxidase inhibitors (MAOIs], selective serotonin reuptake inhibitors (SSRIs), and perhaps venlafaxine, and most do not respond well to tricyclic antidepressants (TCAs] (Davidson et al. 1982 Liebowitz et al. 1988 Quitkin et al. 1988, 1991). Despite these data, TCAs unfortunately have been the first choice for most atypical patients until SSRIs were introduced. 

Clerc GE, Ruimy P, Verdeau Pailles J A double-bhnd comparison of venlafaxine and fluoxetine in patients hospitabzed for major depression and melancholia the Venlafaxine Erench Inpatient Study Group. Int Clin Psychopharmacol 9 139-143, 1994... 

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