Venlafaxine Clomipramine

FIGURE 2.6 Serotonergic synapse. Serotonin binds to at least seven different receptors. The most relevant are the 5-HTi receptors (1), 5-HT2 receptors (2), and 5-HT3 receptors (3). Antagonists of the 5-HT2 receptor include nefazodone and the majority of atypical antipsychotic drugs. The serotonin transporter (4) pumps serotonin back into the serotonergic neuron, which can be blocked by drugs such as venlafaxine, clomipramine, imipramine, and amitriptyline. 

If patient Is taking any agent that can Inhibit serotonin reuptake (e.g., SSRIs, sibutramlne, tramadol, mllnacipran, duloxetine, venlafaxine, clomipramine, etc.)... 

Antidepressants are used in the treatment of neuropathic pain and headache. They include the classic tricyclic compounds and are divided into nonselective nor-adrenaline/5-HT reuptake inhibitors (e.g., amitriptyline, imipramine, clomipramine, venlafaxine), preferential noradrenaline reuptake inhibitors (e.g., desipramine, nortriptyline) and selective 5-HT reuptake inhibitors (e.g., citalopram, paroxetine, fluoxetine). The reuptake block leads to a stimulation of endogenous monoaminer-gic pain inhibition in the spinal cord and brain. In addition, tricyclics have NMDA receptor antagonist, endogenous opioid enhancing, Na+ channel blocking, and K+ channel opening effects which can suppress peripheral and central sensitization. Block of cardiac ion channels by tricyclics can lead to life-threatening arrhythmias. The selective 5-HT transporter inhibitors have a different side effect profile and are safer in cases of overdose [3]. 

Decision analytic models have been constmcted to compare the costs of TCAs with those of SSRIs and other compounds. These comparisons have included imipramine or amitriptyline versus paroxetine or sertraline (Stewart, 1994) imipramine versus paroxetine Qonsson and Bebbington, 1994 McFarland, 1994 Lapierre et al, 1995) fluoxetine versus amitriptyline, clomipramine, doxepin and imipramine (Le Pen et al, 1994) venlafaxine versus amitriptyline, desipramine. 

Panic disorder SSRIs Venlafaxine XR Alprazolam Clomipramine Clonazepam Imipramine Phenelzine... 

The most effective treatment for cataplexy is the tricyclic antidepressants, fluoxetine, or venlafaxine. Imipramine, protriptyline, clomipramine, fluoxetine, and nortriptyline are effective in about 80% of patients. 

Tricyclic drugs have, as the name implies, a three-ring structure, and interfere with reuptake of norepinephrine and/or serotonin into axon terminals. Tricyclic drugs include imipramine (Tofranil), amitriptyline (Elavil), clomipramine (Anafranil), and nortriptyline (Pamelor, Aventil). Tricyclics have the occasional but unfortunate cardiovascular side effects of arrhythmia and postural hypotension. Newer, nontricyclic antidepressants have been developed that are collectively referred to as SSRIs. These have a potent and selective action on serotonin, and lack the cardiovascular side effects of the tricyclics. These include fluoxetine (Prozac), paroxetine (Paxil), sertraline (Zoloft), and fluvoxamine (Luvox). A fifth SSRI, citalopram (Celexa) has been used in Europe and has recently been approved in the United States. Venlafaxine (Effexor) blocks reuptake of norepinephrine and serotonin, while bupropion (Wellbutrin) acts on both dopamine and norepinephrine. 

Solid phase extraction (SPE) has been used to efficiently extract several types of antidepressants, which can then be conveniently analyzed on GC-NPD. One assay extracted and analyzed viloxazine, venlafaxine, imipramine, desipramine, sertraline, and amoxapine from whole blood in one procedure (Martinez et al., 2002). The same laboratory analyzed fluoxetine, amitriptyline, nortriptyline, trimipramine, maprotiUne, clomipramine, and trazodone in whole blood in one assay (Martinez et al., 2003). SPE has also been used for the simultaneous analysis of TCAs and their metabolites by de la Torre et al. (1998). 

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. 

Amitriptyline, clomipramine, imipramine, desipramine, nortriptyline, trimipramine, AT-desmethylclomipramine, fluvoxamine, norfluoxetine, paroxetine, venlafaxine, sertraline Neuroleptics... 

Venlafaxine is a serotonin and noradrenaline reuptake inhibitor (SNRI). It shares these properties with the TCAs amitriptyhne, clomipramine and imip-ramine, but it is the first selective SNRI, with low affinity for muscarinic, histaminic and a-adrenergic receptors. At low doses serotonergic effects predominate, but at higher doses the reuptake of noradrenaline is significantly blocked (Melichar et al. 2001). It is available as immediate and extended release (XR) preparations. 

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. 

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... 

ADHD, attention-deficit hyperactivity disorder BP, blood pressure CLO, clomipramine FLX, fluoxetine IMP, imipramine N, total number of subjects in study ( ), number of preschool-age subjects in study P, pulse rate PDD-NOS, pervasive developmental disorder, not otherwise specified SE, side effect VNF, venlafaxine. DSM-III-R or DSM-IV criteria used not specified by authors. 

Another approach to correct neurotransmission is to inhibit the reuptake of the neurotransmitters into their presvnaptic endings. If the presynaptic reuptake mechanism of a neurotransmitter is blocked then more of the neurotransmitter will stay in the synaptic cleft and be functionally available. Many antidepressant drugs, called reuptake inhibitors , are thought to act via this mechanism. If selective for serotonin they are called selective serotonin reuptake inhibitors (SSRIs, Chapter 1), but if selective for both serotonin and noradrenaline they are called serotonin noradrenaline reuptake inhibitors (SNRIs). Most older antidepressants, such as the tricyclic compounds amitriptyline, imipramine and clomipramine, have little specificity for any of the neurotransmitters fluoxetine, paroxetine, citalopram and a few others are specific for serotonin venlafaxine is a representative of the SNRIs. A more recent mixed-uptake inhibitor is mirtazepine, and some similar compounds are about to be launched. 

Treatment of GAD can be undertaken using a number of pharmacological agents. Benzodiazepines have been found to be superior to placebo in several studies and all benzodiazepines appear to be equally effective. However, side effects include sedation, psvchomotor impairment, amnesia and tolerance (Chapter 1). Recent clinical data indicate that SSRIs and SNRIs are effective in the treatment of acute GAD symptoms. Venlafaxine, paroxetine and imipramine have been shown to be effective antianxiety medications in placebo-controlled studies. Case studies also indicate the usefulness of clomipramine, nefazodone, mirtazapine, fluoxetine and fluvoxamine in GAD. Buspirone, a 5-HTla receptor partial agonist, has been shown to be effective in several placebo-controlled, double-blind trials (Roy-Byme and Cowley, 2002). Buspirone has a later onset of action than both benzodiazepines and SSRIs but with the advantage of being non-addictive and non-sedating. 

With this caveat in mind, each side of the debate has evidence to support its position. The evidence is first summarized supporting the position that SSRIs are less effective than are some other antidepressants (particularly those with dual effects on both serotonin and NE CNS systems) in patients with more severe depression or who are hospitalized. Danish investigators in two double-blind, active-controlled studies found that clomipramine produced a superior response with either paroxetine or citalopram in the treatment of patients hospitalized for major depression (116, 117). Two double-blind studies also have shown that venlafaxine and mirtazapine were more effective than fluoxetine in patients hospitalized with depression ( 114,118). Finally, there are studies showing that the addition of desipramine (one of the most selective NE reuptake inhibitors) to an SSRI can convert nonresponders or pamal responders to full response ( 119, 119a, 120). 

MAOIs, TCAs, lithium, clomipramine (alone or with topical steroids), fluoxetine, and fluvoxamine may reduce the frequency and intensity of this disorder ( 210, 226, 255, 256, 257, 258, 259, 260 and 261) however, controlled trials are needed to conclusively establish efficacy. Relapse after initial improvement has also been reported, however. Data also indicate that both trichotillomania and OCD may respond to venlafaxine ( 262, 263). For children, such treatments should be reserved for only those with the more severe, refractory forms. 

The majority of positive studies have found that later generation antidepressants, especially those with strong serotonergic effects, are effective and may have a more rapid onset of action when used for PMDD (27). Thus, studies with SSRIs (e.g., fluoxetine, sertraline), nefazodone, venlafaxine, and clomipramine have all shown promise. In several studies, luteal phase dosing has been as effective or more effective than continuous dosing in women with PMDD. 

OFFICIAL NAMES Amitriptyline (Elavil), amoxapine (Asendin), bupropion (Wellbutrin), citalopram (Celexa), clomipramine (Anafranil), desipramine (Norpramin), doxepin (Sinequan), fluoxetine (Prozac), imipramine (Norfranil, Tofranil), isocarboxazid (Marplan), maprotiline (Ludiomil), mirtazapine (Remeron), nefazodone (Serzone), nortriptyline (Aventyl, Pamelor), paroxetine (Paxil), phenelzine (Nardil), protriptyline (Vivactil), sertraline (Zoloft), thioridazine (Mellaril), tranylcypromine (Parnate), trazodone (Desyrel), trimipramine (Sur-montil), venlafaxine (Effexor) the herb St. John s wort (Hypericum perforatum) is sold over-the-counter without prescription STREET NAMES Happy pills... 

Cyt 2D6 metabolizes haloperidol, risperidone, thioridazine, sertindole, olanzapine and clozapine common substrates - fluoxetine, paroxetine, sertraline, venlafaxine, amitriptyline, clomipramine, desipramine, imipramine, nortriptyline, propranolol, metoprolol, timolol, codeine, encainide, flecanide. Common inhibitors - paroxetine, sertraline, fluoxetine. 

Imipramine, desipramine, amitriptyline, nortriptyline, trimipramine, clomipramine, lofepramine, amoxapine, dosulepin, maprotiline, mianserin, setiptiline, trazodone, fluvoxamine, paroxetine, milnacipram, sulpiride, tandspirone, methylpheni-date, melitracen Amitriptyline, imipramine, trimipramine, clomipramine, citalopram, fluoxetine, fluvoxamine, paroxetine, sertraline, venlafaxine, reboxetine, viloxazine, doxepin, maprotiline, mianserine, mirtazapine, moclobemide, trazodone, opipramol (and some metabolites)... 

These selective serotonin reuptake inhibitors (SSRIs) include fluoxetine (Prozac), sertraline (Zoloft), paroxetine (Paxil), fluvoxamine (Luvox), citalopram (Celexa), and, most recently, escitalopram (Lexapro see the appendix). These drugs block the removal of the neurotransmitter serotonin from the synaptic cleft. A number of other antidepressants are potent nonselective serotonin reuptake inhibitors (NSRIs). These include the atypical venlafaxine (Effexor) and the tricyclic clomipramine (Anafra-nil). Nefazodone (Serzone) has been withdrawn from the market due to liver damage. 

In major depression, the efficacy of mirtazapine is comparable to that of amitriptyline, clomipramine, doxepin, fluoxetine, paroxetine, citalopram, and venlafaxine. 

Norepinephrine-serotonin reuptake inhibitors Amitriptyline (Elavil) Clomipramine (/Vnafranil) Duloxetine (Cymbalta) Imipramine (Tofranil) Venlafaxine (Effexor)... 

PROPAFENONE I. ANTIARRHYTHMICS - disopyra-mide, procainamide 2. ANTIBIOTICS - macrolides (especially azithromycin, clarithromycin, parenteral erythromycin, telithromycin), quinolones (especially moxifloxacin), quinupristin/ dalfopristin 3. ANTICANCER AND IMMUNOMODULATING DRUGS -arsenic trioxide 4. ANTIDEPRESSANTS - TCAs, venlafaxine 5. ANTIEMETICS-dolasetron 6. ANTIFUNGALS-fluconazole, posaconazole, voriconazole 7. ANTIHISTAMINES - terfenadine, hydroxyzine, mizolastine 8. ANTI-M ALARIALS - artemether with lumefantrine, chloroquine, hydroxychloroquine, mefloquine, quinine 9. ANTIPROTOZOALS - pentamidine isetionate 10. ANTIPSYCHOTICS-atypicals, phenothiazines, pimozide II. BETA-BLOCKERS - sotalol 12. BRONCHODILATORS -parenteral bronchodilators 13. CNS STIMULANTS - atomoxetine Risk of ventricular arrhythmias, particularly torsades de pointes Additive effect these drugs prolong the Q-T interval. Also, amitriptyline, clomipramine and desipramine levels may be t by propafenone. Amitriptyline and clomipramine may t propafenone levels. Propafenone and these TCAs inhibit CYP2D6-mediated metabolism of each other Avoid co-administration... 

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