Interaction between levothyroxine and indinavir in a patient with HIV infection

Medications and Food Interfering with the Bioavailability of Levothyroxine: A Systematic Review

Purpose

Levothyroxine is a common prescribed drug. Many medications and food, however, can interfere with its bioavailability. The aim of this review was to summarize the medications, food and beverages that interact with levothyroxine and to assess their effects, mechanisms and treatments.

Methods

A systematic review on interfering substances that interact with levothyroxine was performed. Web of Science, Embase, PubMed, the Cochrane library, grey literature from other sources and the lists of references were searched for human studies comparing the levothyroxine efficacy with and without interfering substances. The patient characteristics, drug classes, effects and mechanism were extracted. The NHLBI study quality assessment tools and the JBI critical appraisal checklist were used to assess the quality of included studies.

Results

A total of 107 articles with 128 studies were included. Drugs interactions were revealed in calcium and iron supplements, proton pump inhibitors, bile acid sequestrants, phosphate binders, sex hormones, anticonvulsants and other drugs. Some food and beverage could also induce malabsorption. Proposed mechanisms included direct complexing, alkalization, alteration of serum thyroxine-binding globulin levels and acceleration of levothyroxine catabolism via deiodination. Dose adjustment, administration separation and discontinuation of interfering substances can eliminate the interactions. Liquid solutions and soft-gel capsules could eliminate the malabsorption due to chelation and alkalization. The qualities of most included studies were moderate.

Conclusion

Lots of medications and food can impair the bioavailability of levothyroxine. Clinicians, patients and pharmaceutical companies should be aware of the possible interactions. Further well-designed studies are needed to provide more solid evidence on treatment and mechanisms.

HIV/AIDS-related hyponatremia: an old but still serious problem

Hyponatremia is the most common electrolyte disorder in hospitals. Many medical illnesses, including congestive heart failure, liver failure, renal failure and pneumonia, may be associated with hyponatremia. In addition, hyponatremia in patients with the acquired immunodeficiency syndrome (AIDS) and AIDS-related complex (ARC) was first reported in 1993. The evidence suggests that severe hyponatremia is associated with increased morbidity and mortality in human immunodeficiency virus (HIV)/AIDS patients; however, the incidence of hyponatremic syndrome in HIV/AIDS patients remains very high in clinical practice, as almost 40% of HIV/AIDS inpatients in Xinjiang, a developing region of China, are hyponatremic. A method for identifying the pathogenesis and therapeutic treatments for hyponatremia in HIV/AIDS patients is needed. This review focuses on the clinical and pathophysiological aspects of hyponatremia and highlights the causes, presentation and treatment recommendations for hyponatremic patients with HIV/AIDS.

Impact of thyroid function abnormalities on reproductive hormones during menstrual cycle in premenopausal HIV infected females at NAUTH, Nnewi, Nigeria

BACKGROUND

This was a prospective study designed to evaluate the impact of thyroid function abnormalities on reproductive hormones during menstrual cycle in HIV infected females at Nnamdi Azikiwe University Teaching Hospital Nnewi, South-East Nigeria.

METHODS

The study randomly recruited 35 Symptomatic HIV infected females and 35 Symptomatic HIV infected females on antiretroviral therapy (HAART) for not less than six weeks from an HIV clinic and 40 apparently heathy control females among the hospital staff of NAUTH Nnewi. They were all premenopausal females with regular menstrual cycle and aged between 15-45 years. Blood samples were collected at follicular and luteal phases of their menstrual cycle for assay of Thyroid indices (FT3, FT4 and TSH) and Reproductive indices (FSH, LH, Estrogen, Progesterone, Prolactin and Testosterone) using ELISA method.

RESULTS

The result showed significantly higher FSH and LH but significantly lower progesterone (prog) and estrogen (E2) in the test females compared to control females at both phases of menstrual cycle (P<0.05). There was significantly lower FT3 but significantly higher TSH value in Symptomatic HIV females (P<0.05). FSH, LH and TSH values were significantly lowered while prog and FT3 were significantly higher in Symptomatic HIV on ART compared to Symptomatic HIV females (P<0.05). FT3, FT4, Prog and E2 were inversely correlated while FSH and LH were positively correlated with duration of HIV infection in HIV females (P<0.05 respectively). There was a direct correlation between CD4+ count and FT3 while inverse correlation was found between CD4+ count and TSH levels (P<0.05).

DISCUSSION

The present study demonstrated hypothyroidism with a significant degree of primary hypogonadism in Symptomatic HIV infected females at both follicular and luteal phases of menstrual cycle which tends to normalize on treatments.

Dosing Recommendations for Concomitant Medications During 3D Anti-HCV Therapy

The development of direct-acting antiviral (DAA) agents has reinvigorated the treatment of hepatitis C virus infection. The availability of multiple DAA agents and drug combinations has enabled the transition to interferon-free therapy that is applicable to a broad range of patients. However, these DAA combinations are not without drug-drug interactions (DDIs). As every possible DDI permutation cannot be evaluated in a clinical study, guidance is needed for healthcare providers to avoid or minimize drug interaction risk. In this review, we evaluated the DDI potential of the novel three-DAA combination of ombitasvir, paritaprevir, ritonavir, and dasabuvir (the 3D regimen) with more than 200 drugs representing 19 therapeutic drug classes. Outcomes of these DDI studies were compared with the metabolism and elimination routes of prospective concomitant medications to develop mechanism-based and drug-specific guidance on interaction potential. This analysis revealed that the 3D regimen is compatible with many of the drugs that are commonly prescribed to patients with hepatitis C virus infection. Where interaction is possible, risk can be mitigated by paying careful attention to concomitant medications, adjusting drug dosage as needed, and monitoring patient response and/or clinical parameters.

HIV and thyroid dysfunction

Human Immunodeficiency virus (HIV) infection and Acquired Immunodeficiency Syndrome (AIDS) are associated with dysfunction of many endocrine organs and their axis. HIV infectivity leads to altered metabolism, poor oral intake and increased prevalence of weight loss and wasting which may have a role in thyroid dysfunction. Overt thyroid dysfunction occurs at similar rates as the general population while subclinical disease such as nonthyroidal illness (sick euthyroid syndrome), subclinical hypothyroidism and isolated low T4 levels are more frequent. Moreover, HAART therapy can complicate thyroid function further through drug interactions and the immune reconstitution inflammatory syndrome (IRIS). In this review we report the common thyroid dysfunctions associated with HIV before and after HAART therapy. We discuss presentation, diagnostic work up, treatment and follow up in each condition.

Antiretroviral drug interactions: overview of interactions involving new and investigational agents and the role of therapeutic drug monitoring for management

Antiretrovirals are prone to drug-drug and drug-food interactions that can result in subtherapeutic or supratherapeutic concentrations. Interactions between antiretrovirals and medications for other diseases are common due to shared metabolism through cytochrome P450 (CYP450) and uridine diphosphate glucuronosyltransferase (UGT) enzymes and transport by membrane proteins (e.g., p-glycoprotein, organic anion-transporting polypeptide). The clinical significance of antiretroviral drug interactions is reviewed, with a focus on new and investigational agents. An overview of the mechanistic basis for drug interactions and the effect of individual antiretrovirals on CYP450 and UGT isoforms are provided. Interactions between antiretrovirals and medications for other co-morbidities are summarized. The role of therapeutic drug monitoring in the detection and management of antiretroviral drug interactions is also briefly discussed.

Thyroid function abnormalities in HIV-infected patients

Abnormal thyroid function test results are common among human immunodeficiency virus (HIV)-infected patients. Although the prevalence of overt thyroid disease does not appear to be significantly increased in HIV-infected patients, compared with the general population, specific patterns of abnormal thyroid function test findings are more frequently identified among HIV-infected patients. Among patients with advanced acquired immunodeficiency syndrome, nonthyroidal illness (i.e., euthyroid sick syndrome) is common. During antiretroviral therapy, the prevalence of 2 generally asymptomatic conditions (subclinical hypothyroidism, which is characterized by isolated elevated thyroid-stimulating hormone levels, and isolated low free thyroxine levels) is increased. In addition, Graves disease, which is marked by low thyroid-stimulating hormone and elevated thyroxine levels, may occur during immune reconstitution. Testing for thyroid disease among symptomatic patients should begin with measurement of the thyroid-stimulating hormone level. However, there is insufficient evidence to recommend routine thyroid screening of asymptomatic HIV-infected individuals. This review summarizes the current evidence regarding the optimal laboratory evaluation of thyroid function; highlights the causes, presentation, and treatment of thyroid dysfunction in HIV-infected patients; and discusses the controversies regarding screening.