Concomitant Use of Levothyroxine and Proton Pump Inhibitors in Patients with Primary Hypothyroidism: a Systematic Review

Evaluation of the clinical pharmacist's effect on achieving treatment goals in patients with hypothyroidism: a randomized controlled trial

BACKGROUND AND AIM

Hypothyroidism (HoT) treatment involves lifelong thyroxine replacement therapy and regular monitoring. The objective of this study was to assess the impact of clinical pharmacist (CP) intervention in managing drug-related problems (DRPs) on outcomes among patients with HoT receiving levothyroxine (LT4) therapy.

METHOD

A randomized controlled trial involved patients with HoT attending a university hospital's endocrinology and metabolism outpatient clinic from March 2022 to September 2022. Participants were randomly assigned to control (CG) and intervention groups (IG). CP identified and classified DRPs based on Pharmaceutical Care Network Europe (PCNE) v9.1 criteria. The validated version of the Morisky-Green-Levine (MGL) 4-question scale was used to measure adherence. All patients included in the study were assessed during their first visit and again two months later at their second visit.

RESULTS

43 patients were assigned to the CG (n = 25) and IG (n = 18). Diabetes (21.6 vs. 20.5%) and hypertension (16.2% vs. 11.7%) were the most prevalent comorbidities in both the CG and IG, respectively. A total of 118 DRPs belonging to both groups were detected. In the IG group, the total number of DRPs significantly decreased from 66 to 24, and the total potential drug-drug interactions (pDDIs) decreased from 21 to 0 between the first and second visits (p < 0.001). CG and IG patients had no difference in adherence levels at the first and second visits (p > 0.05). A statistically significant increase in adherence to the time of taking the medication was observed between the first and second visits in IG (55.5% vs. 94.4%, p = 0.008).

CONCLUSION

This study highlights the frequent occurrence of DRPs and LT4 therapy adherence problems in patients with HoT. The findings suggest that the intervention of CPs, by increasing adherence to LT4 therapy and decreasing DRPs, could significantly contribute to improving patients' treatment outcomes.

TRIAL REGISTRATION

This study protocol has been retrospectively registered at ClinicalTrials.gov (NCT06408909) at 06/05/2024.

Thyroid hormone replacement therapy in dialysis/renal insufficiency patients

Dialysis/renal insufficiency patients are often accompanied by hypothyroidism due to renal damage, the mechanisms of which are complex. The use of thyroid hormone replacement therapy in such patients has become an important clinical issue. This article reviews the mechanism of hypothyroidism in dialysis/renal insufficiency patients and describes the importance and precautions of thyroid hormone replacement therapy to provide a reference for clinical diagnosis and treatment.

The interplay between vitamin C and thyroid

INTRODUCTION

Vitamin C (ascorbic acid) is a water-soluble vitamin, that plays a key role in the prevention and treatment of scurvy. As vitamin C is an antioxidant and thyroid function may be affected and may affect vitamin C levels, for the first time, we aimed to provide a detailed review of all human studies evaluating the different roles of vitamin C in the thyroid gland. Thyroid cancers, goitre, Graves' disease and other causes of hyperthyroidism and hypothyroidism were the conditions discussed in this study. Furthermore, vitamin C addition to other medications such as levothyroxine was also reviewed.

METHODS

In this study, we reviewed the relevant literature regarding the association between vitamin C and thyroid diseases using original studies from PubMed, Scopus, Embase, and Web of Science.

RESULTS

In this review, we found anti-cancer effects for intravenous (IV) administration of vitamin C in addition to the beneficial effects of using it in combination with radiotherapy and chemotherapy. As autoimmune diseases affect some antioxidant markers, some studies reported a significant difference in blood vitamin C levels in patients with autoimmune thyroid diseases such as Graves' disease. Despite many studies evaluating the effects of IV administration of vitamin C in mentioned diseases, there is a lack of evidence for oral consumption of vitamin C.

CONCLUSIONS

To conclude, there is a lack of evidence, especially clinical trials, for the therapeutic effects of vitamin C on thyroid diseases; however, promising results were reported in some studies in the literature.

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.

Pharmacokinetic Interaction of Anaprazole, Amoxicillin and Clarithromycin after Single-Dose Simultaneous Administration and the Effect of Adding Bismuth on Their Pharmacokinetics in Healthy Male Chinese Subjects

BACKGROUND AND OBJECTIVE

Helicobacter pylori-positive ulcers are treated with a proton pump inhibitor (PPI) + two antibiotics with/without bismuth. The objective of this study was to investigate the pharmacokinetic interaction of the novel PPI anaprazole, amoxicillin and clarithromycin with/without bismuth.

METHODS

This single-centre, randomised, open-label phase 1 pharmacokinetic study included healthy Chinese male participants, comprising two cohorts (cohort 1, 4 × 4 crossover design; cohort 2, 2 × 2 crossover design). In cohort 1, 24 participants received four treatment cycles with a different treatment in each cycle; the washout period between cycles was 9 days. Participants were randomly assigned to one of the following four treatment sequences (1:1:1:1): anaprazole sodium enteric-coated tablet 20 mg monotherapy, amoxicillin 1000 mg monotherapy, clarithromycin 500 mg monotherapy, and a three-drug combination (anaprazole 20 mg, amoxicillin 1000 mg and clarithromycin 500 mg). During each treatment cycle, study drugs were administered twice daily for four consecutive days and once in the morning on the fifth day. Cohort 2 participants were administered a single dose of the three-drug combination and a single dose of a four-drug combination (three-drug combination + bismuth 0.6 g) with a washout period of 11 ± 2 days between treatments. Blood samples were collected for pharmacokinetic analysis.

RESULTS

Twenty-nine of 32 enrolled participants (cohort 1, n = 24; cohort 2, n = 8) completed the study. There were no significant differences in exposure or time to reach maximum concentration (T_max) between each single drug or the three-drug combination (cohort 1) or between the three- and four-drug combinations (cohort 1) for any of the drugs/metabolites.

CONCLUSIONS

Dose adjustments for individual drugs are not necessary with combined dosing of anaprazole, amoxicillin, clarithromycin and bismuth.

Daily requirement of softgel thyroxine is independent from gastric juice pH

BACKGROUND

Softgel levothyroxine (LT4) preparation showed a better in vitro dissolution profile at increasing pH as compared to tablet LT4 preparation. Clinical studies suggested a better performance of softgel LT4 preparation in patients with gastric disorders but whether this finding is related to gastric juice pH variation in vivo is not known.

METHODS

Twenty-eight hypothyroid patients (24F/4M; median age=50 treated with tablet LT4 (median dose= 1.65 µg/kg/day) and with stable thyroid stimulating hormone (TSH) values on target (<0.8-2.5> mU/l) have been shifted to softgel LT4 preparation. The dose of softgel LT4 has been titrated to obtain a similar individual serum TSH value. All subjects followed a specific treatment schedule, taking LT4 in fasting condition and then abstaining from eating or drinking for at least 1 hour. Owing to the presence of long-lasting dyspepsia or of already known gastric disorders, all patients underwent endoscopy, upon informed consent. Gastric juice has been collected during endoscopy to measure gastric pH. Then we plotted the dose of LT4 with the gastric pH obtained in vivo, before and after the switch tablet/softgel preparation in all patients.

RESULTS

Upon the switch tablet/softgel preparation, the therapeutic LT4 dose was very slightly reduced (-6%) in the whole sample. However, the individual variations revealed the existence of two populations, one without any dose reduction (A) and the other showing a dose reduction >20% (B). Upon matching with the actual gastric pH, patients with normal pH (A: n=17; 14F/3M, median 1.52) no showed a lower softgel LT4 requirement. Instead, among patients with reduced gastric acid production (B: n=11; 10F/1M, median pH 5.02) the vast majority (10/11; 91%, p<0.0001) benefited from a lower dose of softgel LT4 (median = -23%, p<0.0001). Interestingly, the dose of LT4 in tablet correlated with pH value (Spearman's ρ =0.6409; p = 0.0002) while softgel dose was independent from gastric juice pH (Spearman's ρ =1.952; p = 0.3194).

CONCLUSIONS

These findings provide evidence that softgel LT4 preparation is independent from the actual gastric pH in humans and may represent a significant therapeutic option in patients with increased LT4 requirement, owed to disorders impairing the gastric acidic output.

Liquid levothyroxine formulations in patients taking drugs interfering with L-T4 absorption

PURPOSE

To describe the current knowledge on thyroid hormonal profile in patients on liquid L-T4 therapy and drugs known to interfere with L-T4 absorption.

METHODS

A PubMed/MEDLINE, Web of Science, and Scopus research was performed. Case reports, case series, original studies and reviews written in English and published online up to 31 August 2022 were selected and reviewed. The final reference list was defined based on the relevance of each paper to the scope of this review.

RESULTS

The available data showed that novel levothyroxine formulations circumvent gastric pH impairment due to multiple interfering drugs such as proton pump inhibitors, calcium or iron supplements, sevelamer, aluminum/magnesium hydroxide and sodium alginate.

CONCLUSION

New formulations can be taken simultaneously with drugs interfering with L-T4 absorption, in particular liquid formulations. Softgel capsules need more studies to support these data.

Functional thyroid disorders in the pharmacy setting: How can we help our patients?

Functional thyroid disorders (hypothyroidism and hyperthyroidism) are amongst the most common endocrine disorders pharmacists encounter on a daily basis. They are highly prevalent in iodine-replete areas, and affect women about 10 times more often than man. Hypothyroidism (thyroid hormone deficiency) is usually caused by Hashimoto's thyroiditis, an autoimmune disorder that leads to gradual thyroid destruction. The drug-of-choice for treating hypothyroidism is levothyroxine, a synthetic form of thyroxine. Key points which need to be discussed with patients who are prescribed levothyroxine for the first time are when/how to administer this drug, how its effects are monitored, what drugs may affect its efficacy, and the importance of properly treating hypothyroidism during pregnancy. Hyperthyroidism (increased production of thyroid hormones) is most often caused by Graves' disease, another thyroid autoimmune disorder in which stimulatory autoantibodies against the TSH receptor lead to increased thyroid function. Graves' disease is most commonly treated with thionamide drugs (thiamazole, carbimazole or propylthiouracil) and patients using these drugs should be advised on the monitoring requirements, duration of treatment, and how to recognize possible serious adverse effects (agranulocytosis and hepatotoxicity), and informed that these drugs must be used during pregnancy in order to reduce the risk of adverse outcomes for the mother and baby.