Antidepressants dosages

From the evidence available to date, the reversible, short-acting MAO inhibitor moclobemide, which is available in several countries (but not the USA), appears to be relatively free of this interaction. (The selective MAO-B inhibitor selegiline loses selectivity at antidepressant dosage. Because its action is on the enzyme that metabolizes dopamine, it is most useful in the treatment of Parkinson s disease [Chapter 28 Pharmacologic Management of Parkinsonism Other Movement Disorders].)... 

For women with premenstrual exacerbation of an underlying depression, severe PMDD, or climacteric depression, a 6- to 12-month course of an antidepressant is recommended. Some women benefit from continuous antidepressant dosing with an intermittent increase in dose prior to the onset of symptoms and a reduction in dose at the onset of menses. Varying the antidepressant dosage and adding supplemental medications based on menstruation-related symptoms have been shown empirically to be helpful. It may be necessary to try several different treatments to find an acceptable therapy. 

A comparative study of 99 patients taking amitriptyline or nortriptyline alone, and 60 other patients also taking perphenazine 10 mg daily, found that although the tricyclic antidepressant dosages were the same, the plasma tricyclic antidepressant levels of the perphenazine group were up to 70% higher. ... 

MISCELLANEOUS ANTIDEPRESSANTS. An uncommon but potentially serious adverse reaction of trazodone is priapism (a persistent erection of die penis). If not treated within a few hours, priapism can result in impotence The nurse instructs the patient to report any prolonged or inappropriate penile erection. Use of the drug is discontinued immediately and the primary care provider notified. Injection of a-adrenergic stimulants (eg, norepinephrine) may be helpful in treating priapism. In some cases, surgical intervention may be required. Venlafaxine may cause an increase in die blood pressure. A sustained increase in die blood pressure may indicate that die dosage of venlafaxine needs to be decreased. 

Explains the reason for drug therapy, including the type of antidepressant prescribed, drug name, dosage, and frequency of administration. 

As can be seen in Table 35-7, antidepressants are available in several different dosage forms.13,16-18,29,32 The extended-release... 

Approximately one-third of patients with MDD do not respond satisfactorily to their first antidepressant medication.37 In such cases, the clinician must evaluate the adequacy of antidepressant therapy, including dosage, duration, and patient compliance.17 Treatment reappraisal also should include verification of the patient s diagnosis and reconsideration of clinical factors that could be impeding successful therapy, such as concurrent medical conditions (e.g., thyroid disorder), comorbid psychiatric conditions (e.g., alcohol abuse), and psychosocial issues (e.g., marital stress).16... 

Kirchheiner, J. etal. (2001). CYP2D6 and CYP2C19 genotype-based dose recommendations for antidepressants a first step towards subpopulation-specific dosages. Acta Psychiatr. Scand., 104, 173-92. 

Chinese depressed patients appeared to require lower dosages, with consequently lower plasma concentrations of sertraline compared to Caucasian patients to achieve clinical efficacy (Ng et al, 2006). Again, this finding has supported the fact that Asian patients, especially Chinese, need lower doses of antidepressant drugs than their Western counterparts. 

Some studies compare dietary supplements to sub-therapeutic dosages of prescription medicine. For example, St. John s wort is compared to some of the tricyclic antidepressants. However, the given doses of amitriptyline and imipramine were below the recommended antidepressant doses. 

The answer is a. (Hardman, p 436J The most common side effects associated with tricyclic antidepressants are their anti muscarinic effects, which may be evident in over 50% of patients. Clinically, the anti muscarinic effects may manifest as dry mouth, blurred vision, constipation, tachycardia, dizziness, and urinary retention. At therapeutic plasma concentrations, these drugs usually do not cause changes in the EKG Direct cardiac effects of the tricyclic antidepressants are important in over dosage. 

Sodium bicarbonate administration for cardiac arrest is controversial because there are few clinical data supporting its use, and it may have some detrimental effects. Sodium bicarbonate can be used in special circumstances (i.e., underlying metabolic acidosis, hyperkalemia, salicylate overdose, or tricyclic antidepressant overdose). The dosage should be guided by laboratory analysis if possible. 

Carbamazepine induces the metabolism of antidepressants, anticonvulsants, and antipsychotics, thus, dosage adjustments maybe required. 

Adult Dosages for Currently Available Antidepressant Medication ... 

A 6-week antidepressant trial at a maximum dosage is considered an adequate trial. Patients must be told about the expected lag time of 2 to 4 weeks before the onset of antidepressant effect. 

Given the wide availability and usage of hypericum, manic reactions such as the ones described appear to be uncommon. As expected, concomittant use of hypericum with pharmaceutical antidepressant medication appears to be contraindicated. Although some antidepressant medications can be given in combination, this must be done with caution and with dosage considerations to account for additive or synergistic effects. 

Future directions for research on hypericum may continue the work done in clinical efficacy. More specifically, studies may be of interest that examine its effects in treatment of more severe depression and different subtypes of depression. The comparative efficacy of different hypericum preparations could be further investigated, and optimum dosages need to be established (Linde et al. 1996). Further work is needed to compare hypericum s efficacy and side effects with those of the SSRIs or atypical antidepressants, because published studies to date have only compared it with tricyclics. 

Once an antidepressant is chosen, the side effects can be minimized by starting at a low dose and increasing to the effective dosage range over the first 1-2 weeks. There is wide variability in the timing of treatment response. In most cases, improvement does not begin until the second week of treatment and usually continues for several weeks thereafter. 

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