Selective serotonin reuptake inhibitors (SSRIs) are primary treatment options for major depressive and anxiety disorders. CYP2D6 and CYP2C19 polymorphisms can influence the metabolism of SSRIs, ...thereby affecting drug efficacy and safety. We summarize evidence from the published literature supporting these associations and provide dosing recommendations for fluvoxamine, paroxetine, citalopram, escitalopram, and sertraline based on CYP2D6 and/or CYP2C19 genotype (updates at www.pharmgkb.org).
Predicting antidepressant response has been a clinical challenge for mood disorder. Although several genome-wide association studies have suggested a number of genetic variants to be associated with ...antidepressant response, the sample sizes are small and the results are difficult to replicate. Previous animal studies have shown that knockout of the serotonin receptor 7 gene (HTR7) resulted in an antidepressant-like phenotype, suggesting it was important to antidepressant action. In this report, in the first stage, we used a cost-effective pooled-sequencing strategy to sequence the entire HTR7 gene and its regulatory regions to investigate the association of common variants in HTR7 and clinical response to four selective serotonin reuptake inhibitors (SSRIs: citalopram, paroxetine, fluoxetine and sertraline) in a retrospective cohort mainly consisting of subjects with bipolar disorder (n = 359). We found 80 single-nucleotide polymorphisms (SNPs) with false discovery rate < 0.05 associated with response to paroxetine. Among the significant SNPs, rs7905446 (T/G), which is located at the promoter region, also showed nominal significance (P < 0.05) in fluoxetine group. GG/TG genotypes for rs7905446 and female gender were associated with better response to two SSRIs (paroxetine and fluoxetine). In the second stage, we replicated this association in two independent prospective samples of SSRI-treated patients with major depressive disorder: the MARS (n = 253, P = 0.0169) and GENDEP studies (n = 432, P = 0.008). The GG/TG genotypes were consistently associated with response in all three samples. Functional study of rs7905446 showed greater activity of the G allele in regulating expression of HTR7. The G allele displayed higher luciferase activity in two neuronal-related cell lines, and estrogen treatment decreased the activity of only the G allele. Electrophoretic mobility shift assay suggested that the G allele interacted with CCAAT/enhancer-binding protein beta transcription factor (TF), while the T allele did not show any interaction with any TFs. Our results provided novel pharmacogenomic evidence to support the role of HTR7 in association with antidepressant response.
Nonadherence to prescribed antipsychotic medications places patients with schizophrenia at a greatly increased risk of illness exacerbation and rehospitalization. Identification of risk factors for ...nonadherence is an initial step toward designing effective interventions. This article reviews recent literature on the prevalence of and risk factors for medication nonadherence in patients with schizophrenia.
We searched the MEDLINE/HealthSTAR and PsycINFO databases using combinations of the keywords risk factor(s), adherence, compliance, antipsychotic, neuroleptic, schizophrenia, and psychosis for articles published since 1980 that identified risk factors for medication nonadherence in schizophrenia patients. We included reports that (1) were published in English and (2) specifically examined risk factors for medication nonadherence. Thirty-nine articles met our selection criteria.
Among the 10 reports that met a strict set of study inclusion criteria, we found a mean rate of nonadherence of 41.2%; the 5 reports that met a stricter set of inclusion criteria had a mean nonadherence rate of 49.5%. In the 39 articles reviewed, factors most consistently associated with nonadherence included poor insight, negative attitude or subjective response toward medication, previous nonadherence, substance abuse, shorter illness duration, inadequate discharge planning or aftercare environment, and poorer therapeutic alliance. Findings regarding an association between adherence and medication type were inconclusive, although few studies explored this relationship. Other factors such as age, gender, ethnicity, marital status, education level, neurocognitive impairment, severity of psychotic symptoms, severity of medication side effects, higher antipsychotic dose, presence of mood symptoms, route of medication administration, and family involvement were not found to be consistent predictors of nonadherence. Limitations of the published literature are discussed.
Efforts to improve medication adherence in patients with schizophrenia should target relevant risk factors.
Reports of gabapentin use in diabetic peripheral neuropathy pain stimulate a need for controlled trials to determine its comparative efficacy to the therapeutic standard of amitriptyline ...hydrochloride.
To determine the efficacy of gabapentin compared with amitriptyline in treating diabetic peripheral neuropathy pain.
Prospective, randomized, double-blind, double-dummy, crossover study.
Veterans Affairs San Diego Healthcare System, Ambulatory Care Clinic.
Twenty-eight veterans were referred by their primary care providers. Two patients withdrew before randomization because of no neuropathic pain after washout; a third withdrew for unexpected surgery that required analgesics. Three patients withdrew because of adverse effects and 1 for protocol violation.
Patients with stable glycemic control and neuropathic pain randomized to 6 weeks of therapy with gabapentin, 900 to 1800 mg/d, or amitriptyline hydrochloride, 25 to 75 mg/d, with a 1-week washout before crossover.
Pain relief measured by pain scale with verbal descriptors and global pain score assessment at treatment end.
Participants and investigators were blinded throughout. Mean dosages were of gabapentin, 1565 mg/d, and of amitriptyline hydrochloride, 59 mg/d. Sixty-five percent of patients reached maximum dose with gabapentin and 54% with amitriptyline. Mean score diary analysis showed pain relief with gabapentin and amitriptyline was not significantly different (P = .26). Global data were obtained from 21 of 25 enrolled patients who completed the study. Moderate or greater pain relief was experienced in 11 (52%) of 21 patients with gabapentin and 14 (67%) of 21 patients with amitriptyline. There were no significant period or carry-over effects (P = .35).
Although both drugs provide pain relief, mean pain score and global pain score data indicate no significant difference between gabapentin and amitriptyline. Gabapentin may be an alternative for treating diabetic peripheral neuropathy pain, yet does not appear to offer considerable advantage over amitriptyline and is more expensive. Larger trials are necessary to define gabapentin's place in treating diabetic peripheral neuropathy pain.
Medication adherence with antipsychotics is adversely impacted by the burden of untoward adverse effects. In particular, sexual side-effects may interfere with compliance, but are often underreported ...by patients. Sexual dysfunction related to hyperprolactinemia is commonly described, but ejaculatory disturbance due to potent alpha1 adrenergic antagonism may also occur, and has been reported frequently with certain typical antipsychotics such as thioridazine, but rarely with atypical antipsychotics. Presented here is the case of a 51 year old male with schizophrenia who developed retrograde ejaculation on high dose risperidone therapy (8 mg/day) with prompt resolution of symptoms upon dose reduction. The absence of decreased libido or erectile dysfunction indicates that alpha1 adrenergic antagonism and not low serum testosterone due to hyperprolactinemia is the etiology for this side-effect. This case illustrates another mechanism for sexual adverse effects, and the need for routine inquiry into sexual dysfunction during atypical antipsychotic therapy.
Medication adherence with antipsychotics is adversely impacted by the burden of untoward adverse effects. In particular, sexual side-effects may interfere with compliance, but are often underreported ...by patients. Sexual dysfunction related to hyperprolactinemia is commonly described, but ejaculatory disturbance due to potent alpha1 adrenergic antagonism may also occur, and has been reported frequently with certain typical antipsychotics such as thioridazine, but rarely with atypical antipsychotics. Presented here is the case of a 51 year old male with schizophrenia who developed retrograde ejaculation on high dose risperidone therapy (8 mg/day) with prompt resolution of symptoms upon dose reduction. The absence of decreased libido or erectile dysfunction indicates that alpha1 adrenergic antagonism and not low serum testosterone due to hyperprolactinemia is the etiology for this side-effect. This case illustrates another mechanism for sexual adverse effects, and the need for routine inquiry into sexual dysfunction during atypical antipsychotic therapy.
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