Pharmacological prevention and treatment of opioid-induced constipation in cancer patients: A systematic review and meta-analysis

BACKGROUND

Cancer-related pain often requires opioid treatment with opioid-induced constipation (OIC) as its most frequent gastrointestinal side-effect. Both for prevention and treatment of OIC osmotic (e.g. polyethylene glycol) and stimulant (e.g. bisacodyl) laxatives are widely used. Newer drugs such as the peripherally acting µ-opioid receptor antagonists (PAMORAs) and naloxone in a fixed combination with oxycodone have become available for the management of OIC. This systematic review and meta-analysis aims to give an overview of the scientific evidence on pharmacological strategies for the prevention and treatment of OIC in cancer patients.

METHODS

A systematic search in PubMed, Embase, Web of Science and the Cochrane Library was completed from inception up to 22 October 2022. Randomized and non-randomized studies were systematically selected. Bowel function and adverse drug events were assessed.

RESULTS

Twenty trials (prevention: five RCTs and three cohort studies; treatment: ten RCTs and two comparative cohort studies) were included in the review. Regarding the prevention of OIC, three RCTs compared laxatives with other laxatives, finding no clear differences in effectivity of the laxatives used. One cohort study showed a significant benefit of magnesium oxide compared with no laxative. One RCT found a significant benefit for the PAMORA naldemedine compared with magnesium oxide. Preventive use of oxycodone/naloxone did not show a significant difference in two out of three other studies compared to oxycodone or fentanyl. A meta-analysis was not possible. Regarding the treatment of OIC, two RCTs compared laxatives, of which one RCT found that polyethylene glycol was significantly more effective than sennosides. Seven studies compared an opioid antagonist (naloxone, methylnaltrexone or naldemedine) with placebo and three studies compared different dosages of opioid antagonists. These studies with opioid antagonists were used for the meta-analysis. Oxycodone/naloxone showed a significant improvement in Bowel Function Index compared to oxycodone with laxatives (MD -13.68; 95 % CI -18.38 to -8.98; I2 = 58 %). Adverse drug event rates were similar amongst both groups, except for nausea in favour of oxycodone/naloxone (RR 0.51; 95 % CI 0.31-0.83; I2 = 0 %). Naldemedine (NAL) and methylnaltrexone (MNTX) demonstrated significantly higher response rates compared to placebo (NAL: RR 2.07, 95 % CI 1.64-2.61, I2 = 0 %; MNTX: RR 3.83, 95 % CI 2.81-5.22, I2 = 0 %). With regard to adverse events, abdominal pain was more present in treatment with methylnaltrexone and diarrhea was significantly more present in treatment with naldemedine. Different dosages of methylnaltrexone were not significantly different with regard to both efficacy and adverse drug event rates.

CONCLUSIONS

Magnesium oxide and naldemedine are most likely effective for prevention of OIC in cancer patients. Naloxone in a fixed combination with oxycodone, naldemedine and methylnaltrexone effectively treat OIC in cancer patients with acceptable adverse events. However, their effect has not been compared to standard (osmotic and stimulant) laxatives. More studies comparing standard laxatives with each other and with opioid antagonists are necessary before recommendations for clinical practice can be made.

A case-control study showing low creatinine clearance and high magnesium intake as risk factors for hypermagnesemia in older individuals

According to epidemiological studies, constipation has a negative effect on life expectancy, necessitating appropriate treatment. According to the Pharmaceuticals and Medical Devices Agency (PMDA), patients who have been taking magnesium oxide (MgO) for constipation over a prolonged period, especially those with impaired renal function and older individuals, are at high risk of hypermagnesemia. Therefore, serum Mg levels, which are often not checked in clinical practice, should be monitored in these patients. Thus, to predict elevated serum Mg levels and prevent the development of hypermagnesemia, we aimed to identify the risk factors of hypermagnesemia, especially in the older population. Our study included patients who were prescribed MgO at our hospital between January 1, 2014, and March 31, 2016. Patients who did not meet the inclusion criteria were excluded and matched to adjust for background factors; finally, 35 patients in the hypermagnesemia arm and 140 patients in the non-hypermagnesemia arm were included in the analysis. Multivariate analysis identified estimated creatinine clearance (eCcr) ≤ 28.2 mL/min as a statistically significant risk factor. In addition, MgO dose ≥ 900 mg/day was identified as a risk factor for clinical consideration, although not statistically significant. Furthermore, the incidence of hypermagnesemia was shown to increase to 11.6% for those with MgO dose ≥ 900 mg/day, 27.0% for those with eCcr ≤ 28.2 mL/min, and 53.1% for those with both. Hypermagnesemia may occur in older patients with eCcr ≤ 28.2 mL/min who take more than 900 mg/day of MgO.

Magnesium Oxide in Constipation

Magnesium oxide has been widely used as a laxative for many years in East Asia, yet its prescription has largely been based on empirical knowledge. In recent years, several new laxatives have been developed, which has led to a resurgence in interest and increased scientific evidence surrounding the use of magnesium oxide, which is convenient to administer, of low cost, and safe. Despite these advantages, emerging clinical evidence indicates that the use of magnesium oxide should take account of the most appropriate dose, the serum concentration, drug-drug interactions, and the potential for side effects, especially in the elderly and in patients with renal impairment. The aim of this review is to evaluate the evidence base for the clinical use of magnesium oxide for treating constipation and provide a pragmatic guide to its advantages and disadvantages.

Pediatric bowel preparation: Sodium picosulfate, magnesium oxide, citric acid vs polyethylene glycol, a randomized trial

BACKGROUND

Bowel preparation in children can be challenging.

AIM

To describe the efficacy, safety, and tolerability of sodium picosulfate, magnesium oxide, and citric acid (SPMC) bowel preparation in children.

METHODS

Phase 3, randomized, assessor-blinded, multicenter study of low-volume, divided dose SPMC enrolled children 9-16 years undergoing elective colonoscopy. Participants 9-12 years were randomized 1:1:1 to SPMC ½ dose × 2, SPMC 1 dose × 2, or polyethylene glycol (PEG). Participants 13-16 years were randomized 1:1 to SPMC 1 dose × 2 or PEG. PEG-based bowel preparations were administered per local protocol. Primary efficacy endpoint for quality of bowel preparation was responders (rating of ‘excellent’ or ‘good’) by modified Aronchick Scale. Secondary efficacy endpoint was participant’s tolerability and satisfaction from a 7-item questionnaire. Safety assessments included adverse events (AEs) and laboratory evaluations.

RESULTS

78 participants were randomized, 48 were 9-12 years, 30 were 13-16 years. For the primary efficacy endpoint in 9-12 years, 50.0%, 87.5%, and 81.3% were responders for SPMC ½ dose × 2, SPMC 1 dose × 2, and PEG groups, respectively. Responder rates for 13-16 years were 81.3% for SPMC 1 dose × 2 and 85.7% for PEG. Overall, 43.8% of participants receiving SPMC 1 dose × 2 reported it was ‘very easy’ or ‘easy’ to drink, compared with 20.0% receiving PEG. Treatment-emergent AEs were reported by 45.5% of participants receiving SPMC 1 dose × 2 and 63.0% receiving PEG.

CONCLUSION

SPMC was an efficacious and safe for bowel preparation in children 9-16 years, with comparable efficacy to PEG. Tolerability for SPMC was higher compared to PEG.

Magnesium oxide and hip fracture in the elderly: a population-based retrospective cohort analysis

Using national insurance claims of Taiwan, we found that magnesium oxide (MgO) use is associated with an increased risk of hip fracture in the elderly. Further studies are warranted to explore the mechanisms associated with MgO use that lead to hip fracture.

PURPOSE

The purpose of this study was to investigate the association between MgO use and hip fracture risk in the elderly (age > 65 years).

METHODS

This nationwide population-based retrospective study was conducted from 1996 to 2013. Individuals with (n = 26,069) and without (n = 26,069) MgO use were enrolled after propensity score matching. Primary outcome was a hip fracture. After adjusting for age, sex, comorbidities, and medications, multivariate Cox proportional hazards regression models were used to calculate incidences and risk of hip fracture [hazard ratio (HR)].

RESULTS

During the mean follow-up duration of 4.8 years in the MgO cohort and 5.7 years in the non-MgO cohort, respectively 1547 and 1107 cases developed a hip fracture. MgO use was identified as a risk factor for hip fracture in both univariate [crude HR, 1.68; 95% confidence interval (CI), 1.55-1.81; p < 0.001] and multivariate [adjusted HR (aHR), 1.66; 95% CI, 1.54-1.80; p < 0.001] Cox proportional hazards regression models. The cumulative incidence of hip fracture was significantly higher in the MgO cohort than in the non-MgO cohort (1.23 per 100 person-years vs. 0.74 per 100 person-years, logrank test, p < 0.001).

CONCLUSION

MgO use is an independent risk factor for hip fracture in the elderly.

A Magnesium Oxide Bezoar

A 75-year-old Japanese woman presented with nausea and appetite loss. Computed tomography showed a radiopaque substance in the stomach. Esophagogastroduodenoscopy revealed bezoars in the stomach, which were endoscopically retrieved. The bezoars were mainly composed of magnesium and oxide. Although bezoar formation associated with magnesium oxide consumption is infrequently encountered, the present case indicates that pharmacobezoar should be considered among the differential diagnoses in patients who demonstrate a radiopaque mass in the digestive tract and have a history of magnesium oxide use.

Severe hypermagnesemia induced by magnesium oxide ingestion: a case series

Hypermagnesemia is generally considered an exceptional iatrogenic condition usually caused by magnesium-containing cathartics. In particular, this condition often develops when magnesium-containing cathartics are administered to elderly patients with renal insufficiency or bowel movement dysfunction. Although magnesium oxide (MgO) is widely prescribed as a laxative, serum magnesium concentration has not been examined in most cases. In this report, we present the cases of four elderly patients with constipation and symptomatic hypermagnesemia caused by MgO ingestion, one of which had a lethal course. All of the patients were older than 65 years and with renal dysfunction. In addition, they had difficulties in expressing their symptoms because of cerebrovascular events or dementia. These cases suggest that hypermagnesemia caused by magnesium-containing cathartics is more likely to develop than previously recognized and that physicians should be aware that patients with chronic kidney disease and the elderly are at risk of hypermagnesemia on magnesium administration. We recommend serum magnesium monitoring for high-risk patients after initial prescription or dose increase.

A Pilot Randomized Trial of Oral Magnesium Supplementation on Supraventricular Arrhythmias

Low magnesium may increase the risk of atrial fibrillation. We conducted a double-blind pilot randomized trial to assess adherence to oral magnesium supplementation (400 mg of magnesium oxide daily) and a matching placebo, estimate the effect on circulating magnesium concentrations, and evaluate the feasibility of using an ambulatory heart rhythm monitoring device (ZioPatch) for assessing premature atrial contractions. A total of 59 participants were randomized; 73% were women, and the mean age was 62 years. A total of 98% of the participants completed the follow-up. In the magnesium supplement group, 75% of pills were taken, and in the placebo group, 83% were taken. The change in magnesium concentrations was significantly greater for those given the magnesium supplements than for those given the placebo (0.07; 95% confidence interval: 0.03, 0.12 mEq/L; p = 0.002). The ZioPatch wear time was approximately 13 of the requested 14 days at baseline and follow-up. There was no difference by intervention assignment in the change in log premature atrial contractions burden, glucose, or blood pressure. Gastrointestinal changes were more common among the participants assigned magnesium (50%) than among those assigned the placebo (7%), but only one person discontinued participation. In sum, compliance with the oral magnesium supplementation was very good, and acceptance of the ZioPatch monitoring was excellent. These findings support the feasibility of a larger trial for atrial fibrillation (AF) prevention with oral magnesium supplementation.

Functional Improvement in Rats' Pancreatic Islets Using Magnesium Oxide Nanoparticles Through Antiapoptotic and Antioxidant Pathways

According to undiscovered toxicity and safety of magnesium oxide nanoparticles (MgO NPs) in isolated pancreatic islet cells, this study was designed to examine the effects of its various concentrations on a time-course basis on the oxidative stress, viability, and function of isolated islets of rat's pancreas. Pancreatic islets were isolated and exposed to different MgO NP (<100 nm) concentrations within three different time points. After that, oxidative stress biomarkers were investigated and the best exposure time was selected. Then, safety of MgO NPs was investigated by flow cytometry and fluorescent staining, and levels of insulin secretion and caspase activity were measured. The results illustrated a considerable decrease in oxidative stress markers such as reactive oxygen species (ROS) and lipid peroxidation (LPO) levels of pancreatic islets which were treated by MgO NPs for 24 h. Also, in that time of exposure, cell apoptosis investigation by flow cytometry and insulin test showed that MgO NPs, in a concentration of 100 μg/ml, decreased the rate of apoptotic cells via inhibiting caspase-9 activity and made a significant increase in the level of insulin secretion. Data of function and apoptosis biomarkers correlated with each other. It is concluded that the use of MgO NPs in concentration of as low as 100 μg/ml can induce antiapoptotic, antioxidative, and antidiabetic effects in rat pancreatic islets, which support its possible benefit in islet transplantation procedures.

[Bowel obstruction-induced cholinergic crisis with progressive respiratory failure following distigmine bromide treatment]

A 54-year-old female experienced rapid respiratory failure while being transported in an ambulance to our emergency department for evaluation and management of constipation and abdominal pain. The patient was on treatment with distigmine bromide for postoperative urination disorder and magnesium oxide for constipation. Increased salivary secretions, diminished respiratory excursion, type 2 respiratory failure (PaCO2 : 65 mmHg), low serum cholinesterase, and hypermagnesemia were detected. Imaging studies revealed that the patient had bilateral aspiration pneumonia, fecal impaction in the rectum, and a distended colon causing ileus. The patient was mechanically ventilated and was weaned off the ventilator on day 3. Therapeutic drug monitoring after discharge revealed that the serum level of distigmine bromide on admission was markedly elevated (377.8 ng/mL vs. the normal therapeutic level of 5-10 ng/mL). Distigmine bromide induced a cholinergic crisis with a resultant increase in airway secretions and respiratory failure. In this particular case, orally administered distigmine bromide was excessively absorbed because of prolonged intestinal transit time secondary to fecal impaction and sluggish bowel movement; this caused a cholinergic crisis and hypermagnesemia contributing to respiratory failure. Clinicians should be aware that bowel obstruction in a patient treated with distigmine bromide can increase the risk of a cholinergic crisis.

Cancer mortality in towns in the vicinity of installations for the production of cement, lime, plaster, and magnesium oxide

Our objective was to investigate whether there might be excess cancer mortality in the vicinity of Spanish installations for the production of cement, lime, plaster, and magnesium oxide, according to different categories of industrial activity. An ecologic study was designed to examine municipal mortality due to 33 types of cancer (period 1997-2006) in Spain. Population exposure to pollution was estimated on the basis of distance from town to industrial facility. Using spatial Besag-York-Mollié regression models with integrated nested Laplace approximations for Bayesian inference, we assessed the relative risk of dying from cancer in a 5-km zone around installations, analyzed the effect of category of industrial activity according to the manufactured product, and conducted individual analyses within a 50-km radius of each installation. Excess all cancer mortality (relative risk, 95% credible interval) was detected in the vicinity of these installations as a whole (1.04, 1.01-1.07 in men; 1.03, 1.00-1.06 in women), and, principally, in the vicinity of cement installations (1.05, 1.01-1.09 in men). Special mention should be made of the results for tumors of colon-rectum in both sexes (1.07, 1.01-1.14 in men; 1.10, 1.03-1.16 in women), and pleura (1.71, 1.24-2.28), peritoneum (1.62, 1.15-2.20), gallbladder (1.21, 1.02-1.42), bladder (1.11, 1.03-1.20) and stomach (1.09, 1.00-1.18) in men in the vicinity of all such installations. Our results suggest an excess risk of dying from cancer, especially in colon-rectum, in towns near these industries.

A pilot phase II trial of magnesium supplements to reduce menopausal hot flashes in breast cancer patients

BACKGROUND

We tested if magnesium would diminish bothersome hot flashes in breast cancer patients.

METHODS

Breast cancer patients with at least 14 hot flashes a week received magnesium oxide 400 mg for 4 weeks, escalating to 800 mg if needed. Hot flash score (frequency × severity) at baseline was compared to the end of treatment.

RESULTS

Of 29 who enrolled, 25 women completed treatment. The average age was 53.5 years; six African American, the rest Caucasian; eight were on tamoxifen, nine were on aromatase inhibitors, and 14 were on anti-depressants. Seventeen patients escalated the magnesium dose. Hot flash frequency/week was reduced from 52.2 (standard error (SE), 13.7) to 27.7 (SE, 5.7), a 41.4% reduction, p = 0.02, two-sided paired t test. Hot flash score was reduced from 109.8 (SE, 40.9) to 47.8 (SE, 13.8), a 50.4% reduction, p = 0.04. Of 25 patients, 14 (56%) had a >50% reduction in hot flash score, and 19 (76%) had a >25% reduction. Fatigue, sweating, and distress were all significantly reduced. Side effects were minor: two women stopped the drug including one each with headache and nausea, and two women had grade 1 diarrhea. Compliance was excellent, and many patients continued treatment after the trial.

CONCLUSIONS

Oral magnesium appears to have helped more than half of the patients and was well tolerated. Side effects and cost ($0.02/tablet) were minimal. A randomized placebo-controlled trial is planned.

[Influence of impaired renal function and magnesium oxide administration on serum magnesium levels in elderly inpatients]

AIM

This study aimed to clarify whether serum magnesium (Mg) levels increased in elderly inpatients with impaired renal function receiving magnesium oxide (MgO) administration.

METHODS

We recruited a total of 1,282 inpatients (505 men, 777 women, mean age 79.6 years) in this study. Fasting blood samples were obtained early in the morning. Serum Mg was measured using xylidyl blue method. Estimated glomerular filtration rate (eGFR) levels were calculated according to the formula for ethnic Japanese, inserting sex, age and serum creatinine (cr) levels into the formula. Inpatients were divided into 5 groups according to eGFR levels (ml/min/1.73 m(2)): <30 eGFR (group 1), ≥ 30 but <60 (group 2), ≥ 60 but <90 (group 3), ≥ 90 but <130 (group 4), and ≥ 130 (group 5). Division into a further 4 groups was also carried out, into the same groups (1-3) as described above and ≥ 90 (group 4). In these subgroups we investigated how serum Mg levels changed according to different eGFR levels, or after being given MgO.

RESULTS

In 552 inpatients not given MgO and 372 given MgO, the percentages of subjects with ≥ 2.7 mg/dl of serum Mg were 38.5% in those not given MgO and 78.5% in those given MgO in group 1, 28.1% and 49%, respectively, in group 2, 0% and 23.1% to 29.6% in groups 3 to 5; the percentage of patients with < 2.4 mg/dl of serum Mg was higher in groups 1 to 5 in those not given MgO than in those given MgO. These findings suggest an increase in serum Mg levels after initiation of MgO administration. At an average of 6.9 months in 22 men and 6.4 months in 39 women, both groups not receiving MgO serum Mg increased significantly, while eGFR reduced considerably. At an average of 6.4 months in 18 men and 10 months in 30 women who received MgO, serum Mg increased considerably, although eGFR did not show any significant change. In 4 cases spanning 4 to 14 months, seesawing alterrations between eGFR and serum Mg were often noted. We measured subjects from the 4 subgroups (divided according to eGFR), comprising 88 inpatients not given MgO, 116 who were given daily doses of 0.5 g to 1.5 g MgO, and 118 who were given daily doses of 2 g to 3 g MgO. In those without MgO serum Mg was markedly higher in group 1 than in groups 3 and 4. In all 4 groups, serum Mg was markedly higher in those given MgO than in those not given MgO. In group 1 only, serum Mg was markedly higher in those given daily doses of 2 g to 3 g than in those given 0.5 g to 1.5 g MgO. In 23 subjects with serum Mg levels of over 3.8 mg/dl (normal range: 1.7 mg/dl to 2.6 mg/dl), 7 not given MgO had markedly lower eGFR levels than 16 given MgO, and the mean levels of serum Mg were similar among these. The highest levels of serum Mg were 5.2 mg/dl in those not given MgO and 5.9 mg/dl in those given MgO.

CONCLUSION

The important factors associated with elevated serum Mg levels noted in this study were: a reduction in eGFR to below 30 ml/min/1.73 m(2), and MgO administration for treatment of chronic constipation and the simultaneous occurrence of the above two factors.

Clinical comparison of postoperative sensitivity for an adhesive resin cement containing 4-META and a conventional glass-lonomer cement

PURPOSE

The aim of this clinical 2-year follow-up study was to compare the postoperative sensitivity of abutment teeth restored with full coverage restorations retained with either conventional glass-ionomer cement or a new adhesive resin cement containing 4-methacrylolyloxyethyl trimellitate anhydride (4-META).

MATERIALS AND METHODS

Sixty patients received 120 full-coverage restorations on vital abutment teeth, cemented with either a glass-ionomer cement (Ketac-Cem) or a new adhesive resin cement (Chemiace II). A randomized split-mouth design and a patient double-blind data acquisition protocol were used. The teeth were examined before cementation, after 1 week, and after 6, 12, and 24 months.

RESULTS

With regard to postcementation sensitivity, a low incidence was observed for both groups. With the adhesive resin cement, little postoperative hypersensitivity was observed after 1 week (13.3%), 6 months (5.9%), 12 months (2.1%), and 24 months (none); results were similar with the conventional glass-ionomer cement Ketac-Cem after 1 week (5.9%), 6 months (5.9%), 12 months (6.4%), and 24 months (none). After 6 months, 2 teeth of the Chemiace II group showed no sensitivity. Endodontic treatment was carried out for these 2 abutment teeth. After 24 months, no cases of postoperative hypersensitivity were recorded for either group.

CONCLUSION

In this study, the incidence of postoperative hypersensitivity after cementation of full-crown restorations with a conventional glass-ionomer cement and a new adhesive resin cement was similar.

A randomized controlled study of effects of dietary magnesium oxide supplementation on bone mineral content in healthy girls

CONTEXT

The role of magnesium (Mg) as a determinant of bone mass has not been extensively explored. Limited studies suggest that dietary Mg intake and bone mineral density are correlated in adults, but no data from interventional studies in children and adolescents are available.

OBJECTIVE

We sought to determine whether Mg supplementation in periadolescent girls enhances accrual of bone mass.

DESIGN

We carried out a prospective, placebo-controlled, randomized, one-year double-blind trial of Mg supplementation.

SETTING

The study was conducted in the Clinical Research Centers at Yale University School of Medicine.

PATIENTS OR OTHER PARTICIPANTS

Healthy 8- to 14-yr-old Caucasian girls were recruited from community pediatricians' offices. Dietary diaries from over 120 volunteers were analyzed, and those with dietary Mg intake of less than 220 mg/d were invited to participate in the intervention.

INTERVENTION

Magnesium (300 mg elemental Mg per day in two divided doses) or placebo was given orally for 12 months.

MAIN OUTCOME MEASURE

The primary outcome measure was interval change in bone mineral content (BMC) of the total hip, femoral neck, Ward's area, and lumbar spine (L1-L4) after 12 months of Mg supplementation.

RESULTS

Significantly increased accrual (P = 0.05) in integrated hip BMC occurred in the Mg-supplemented vs. placebo group. Trends for a positive Mg effect were evident in the pre- and early puberty and in mid-late puberty. Lumbar spinal BMC accrual was slightly (but not significantly) greater in the Mg-treated group. Compliance was excellent; 73% of capsules were ingested as inferred by pill counts. Serum mineral levels, calciotropic hormones, and bone markers were similar between groups.

CONCLUSIONS

Oral Mg oxide capsules are safe and well tolerated. A positive effect of Mg supplementation on integrated hip BMC was evident in this small cohort.

[A man with a classic serious milk-alkali syndrome and a carcinoma of the stomach]

A 42-year-old man was transferred to the Emergency Department after his friends had found him unresponsive and confused in his room. He had been experiencing upper abdominal complaints for a period of several months. He had taken large amounts of a calcium carbonate/magnesium subcarbonate preparation (Rennie) and had consumed at least 3 litres of dairy products per day. His behaviour was reported as being more and more abnormal during the previous few weeks. On admission he was confused and agitated and had involuntary movements of his limbs. Laboratory investigation indicated a triple acid base disorder, i.e. metabolic alkalosis, respiratory alkalosis and high anion gap metabolic acidosis, with severe dehydration. The metabolic alkalosis was caused by the intake of large amounts of dairy and antacids: milk-alkali syndrome. The metabolic acidosis was the result of hypovolaemia and pre-renal renal failure and the respiratory alkalosis was caused by hyperventilation due to the organic psychosyndrome. The patient was treated with volume expansion by isotonic saline and the administration of potassium and he was sedated with low-dose midazolam, which led to a full respiratory compensation of the metabolic alkalosis. A few days following admission, both the plasma calcium concentration and renal function returned to normal; the acid-base disorder completely normalized and the organic psychosyndrome disappeared. On gastroduodenoscopy a gastric ulcer was found; biopsies revealed a signet ring cell adenocarcinoma of the stomach.

Use of cisapride with magnesium oxide in chronic pediatric constipation

Functional constipation in children is a common problem in daily practice, however there is currently no accepted optimal treatment of choice. This study investigated the effect of cisapride in the treatment of pediatric constipation when combined with magnesium oxide (MgO). This prospective study enrolled children with chronic constipation. They were randomly assigned to either MgO (125 mg three times a day for patients weighing less than 20 kg or 250 mg three times a day for those weighing more than 20 kg), or cisapride 0.2 mg/kg (max 5mg/dose) plus MgO for 4 weeks. Twenty-one doctors in 19 major medical centers or hospitals in Taiwan with well- established pediatric departments participated in this study from October 1999 to March 2000. 84 children (51 males, 33 females, 1-7 years of age) with fewer than 2 spontaneous bowel movements per week for at least one month completed the study. After 1 week of therapy, a good response, defined as 3 or more bowel movements per week, was achieved in 30 (68.2%) of children treated with cisapride and MgO compared with 23 (57.5%) children treated with MgO alone (p=n.s.). At the end of the 4-week treatment period, 90.9% of the children in cisapride group compared with 67.5% of the children in MgO group achieved a good response (p=0.013). There was no statistical difference between the two groups in terms of the side effects and stool characteristics. In conclusion, it appears that cisapride in combination with MgO may have a synergistic effect and improves the frequency of stool passage in pediatric functional constipation.

Decalcification in relation to brackets bonded with glass ionomer cement or a resin adhesive

Forty randomly selected patients had brackets bonded on one side of the of the maxillary labial segment with glass ionomer cement. Teeth on the opposite side were bonded with a resin adhesive. Teeth were assessed for decalcification pretreatment, at debond, and at review using a standardized photographic technique and a modified DDE index. The mean number of teeth affected by decalcification and the mean extent of decalcification per tooth increased during the treatment period, but from debond to review both of these measurements decreased for teeth bonded with either material (p)<0.01, t-test). Decalcification appears to become less severe posttreatment, but does not appear to be significantly affected during 12 to 18 months of orthodontic treatment by bonding with glass ionomer cement. Dietary and other environmental factors, including fluoride preparations, may be of greater importance in the prevention of decalcification during fixed appliance therapy.

Human pulmonary responses to experimental inhalation of high concentration fine and ultrafine magnesium oxide particles

Exposure to air polluted with particles less than 2.5 micron in size is associated epidemiologically with adverse cardiopulmonary health consequences in humans. The goal of this study was to characterize human pulmonary responses to controlled experimental high-dose exposure to fine and ultrafine magnesium oxide particles. We quantified bronchoalveolar lavage (BAL) cell and cytokine concentrations, pulmonary function, and peripheral blood neutrophil concentrations in six healthy volunteers 18 to 20 hr after inhalation of fine and ultrafine magnesium oxide particles produced from a furnace system model. We compared postexposure studies with control studies from the same six subjects. Mean +/- standard deviation (SD) cumulative magnesium dose was 4,138 +/- 2,163 min x mg/m3. By weight, 28% of fume particles were ultrafine (<0.1 micron in diameter) and over 98% of fume particles were fine (<2.5 micron in diameter). There were no significant differences in BAL inflammatory cell concentrations, BAL interleukin (IL)-1, IL-6, IL-8, tumor necrosis factor, pulmonary function, or peripheral blood neutrophil concentrations postexposure compared with control. Our findings suggest that high-dose fine and ultrafine magnesium oxide particle exposure does not produce a measurable pulmonary inflammatory response. These findings are in marked contrast with the well-described pulmonary inflammatory response following zinc oxide particle inhalation. We conclude that fine and ultrafine particle inhalation does not result in toxicity in a generic manner independent of particle composition. Our findings support the concept that particle chemical composition, in addition to particle size, is an important determinant of respiratory effects.

High-dose pyridoxine and magnesium administration in children with autistic disorder: an absence of salutary effects in a double-blind, placebo-controlled study

Several reports have described salutary effects such as decreased physical aggression and improved social responsiveness being associated with the administration of high doses of pyridoxine and magnesium (HDPM) in open-labeled and controlled studies of patients with autism. Despite this fact, this intervention remains controversial. A 10-week double-blind, placebo-controlled trial was undertaken to examine both the efficacy and safety of HDPM in autism. Twelve patients were enrolled, and 10 patients (mean age 6 years 3 months) were able to complete the study. HDPM at an average dose of 638.9 mg of pyridoxine and 216.3 mg of magnesium oxide was ineffective in ameliorating autistic behaviors as assessed by the Children's Psychiatric Rating Scale (CPRS), the Clinical Global Impression Scale, and the NIMH Global Obsessive Compulsive Scale. Furthermore, no clinically significant side effects were noted during HDPM administration. A trend for a transient change on the CPRS was found that was possibly due to a placebo response. This study raises doubts about the clinical effectiveness of HDPM in autistic disorder.

A blinded clinical trial comparing conventional cleansing enema, Pico-salax and Golytely for barium enema bowel preparation

An evaluator-blinded randomized clinical trial was undertaken to assess the effectiveness and patient acceptance of three bowel cleansing regimens: conventional cleansing enema, Pico-salax and Golytely.

PATIENTS AND METHODS

One hundred and fifty patients, referred for barium enema examination, were allocated to one of the three regimens. Both the radiographers and the radiologists did not know the method of preparation. Radiographers were requested to enter the patients' data, the number of bowel openings, the patients' comments of the preparation and side effects. Films were reviewed independently by two experienced radiologists for the degree of bowel cleanliness and quality of barium coating.

RESULTS

The mean (standard deviation) of bowel opening frequency for the cleansing enema, Pico-Salax and Golytely were 3.6(4.4), 8.3(4.8) and 7.1(4.2), respectively, with less bowel opening in the cleansing enema. There was less nausea associated with the cleansing enema (P = 0.006), more vomiting with Golytely (P = 0.008), less abdominal fullness with Pico-salax (P = 0.0006), less anorectal irritation with Golytely (P = 0.025), and no difference in the abdominal pain amongst three groups. There was no statistically significant difference in the number of bowel openings between the groups. Patients found that Pico-salax tasted better than Golytely (P = 0.0094) and Golytely was less accepted in the amount of fluid intake (P = 0.0018 and P < 0.0002 comparing Golytely with the cleansing enema and Pico-salax). Chi-squared testing showed no statistically significant difference in bowel cleanliness and quality of barium coating among the three preparations.

CONCLUSIONS

There was no difference in the effectiveness of the three regimens. Pico-salax seems the most acceptable because it has the fewest side effects.

Clinical comparison of postoperative sensitivity for a glass ionomer and a zinc phosphate luting cement

In 60 patients, 120 partial and full-coverage restorations were cemented on vital abutment teeth with either a glass ionomer or a zinc phosphate luting cement. A split-mouth design and a patient blind data acquisition protocol were used. During an average observation period of 17.3 months there were no differences between the two types of luting cements in regard to subjective and clinical parameters. A high incidence of postoperative hypersensitivity, which is often said to accompany the use of glass ionomer luting cements, was not observed. With the cementation method used in this study, the glass ionomer cement Ketac-Cem Maxicap was an acceptable alternative to conventional zinc phosphate cement. Capsule systems make the clinical handling of glass ionomer luting cements safe and easy and should be used routinely in dental practice.

Small bowel obstruction caused by a medication bezoar: report of a case

We report herein the rare case of a 26-year-old woman who developed a small-bowel obstruction caused by a medication "bezoar" or enterolith, following the long-term ingestion of magnesium oxide cathartics for constipation. Medication bezoars resulting from laxatives or cathartics have rarely been reported and we were only able to find two other such cases in the literature.

[Magnesium oxide and tocolysis. Our clinical experience and comparison with beta-mimetic (isoxusprine) therapy]

The authors propose the use of oral Magnesium Oxide in the quantity of 200 mg every 3-4 hours for the tocolytic treatment of the pre-term pain, once intravenous tocolysis has decreased or stopped uterine activity (since it has considerably more rapid effect). This treatment constitutes a valid alternative to the use of Beta Mimetic agents in all cases where their use is contraindicated. In the present study, we followed one heterogeneous group of 130 patients, suffering from premature labor hospitalized in our department. After decreasing the uterine contractions by intravenous isossuprine, sixty patients were subsequently treated with magnesium Oxide, fifty with oral isossisuprine, twenty with a simple antispasmodic and the remaining constituted the control group. The percentage of pre-term births has been almost the same in the first two groups (around 17%). The percentage of the patients who exhibited side effects of Beta Mimetic was 30-40%, against 2% of the patients treated with Magnesium Oxide. The intensity of the symptoms was however so slight in the patients treated with Magnesium Oxide, that it failed to disturb the compliance of the patients which allowed to continue the therapy for the necessary period.

[A case of the milk-alkali syndrome with a small amount of milk and magnesium oxide ingestion--the contribution of sustained metabolic alkalosis induced by hypertonic dehydration]

We described a patient with the milk-alkali syndrome induced by the ingestion of small amount of milk (200 ml/day) and ice cream (145 g/day) and the administration of small dose of absorbable alkali (magnesium oxide 2.0 g/day) for the treatment of chronic constipation. The present case shows not only triads, i.e., hypercalcemia (s-Ca 14.3 mg/dl), metabolic alkalosis (s-HCO3- 37.4 mEq/L), and renal insufficiency (s-Cre 2.3 mg/dl) but also hypernatremia (s-Na 161 mEq/L) and hypertonic dehydration after the frequent episodes of elevated body temperature. The milk-alkali syndrome has been defined as the hypercalcemia with a metabolic alkalosis from a high amount of calcium intake and long term administration of absorbable alkali in any form, usually as calcium carbonate for the treatment of peptic ulcer. As the present case could be distinguished from any other cases previously reported with regard to the amount of calcium (0.4 g/day) and alkali (36 mEq/day) intake and the clinical situations that induced the syndrome, we compared the present case with the previous reports, calculating the amount of calcium and alkali intake from milk and absorbable alkali. After the introduction of the H2 blockers for peptic ulceration, the most cases with milk-alkali syndrome had provoked by the smaller amount of calcium than previously reported, which were associated with the treatment of relatively large amount of alkali (50-150 mEq/day), suggesting the role of sustained metabolic alkalosis for the development. In the present case the metabolic alkalosis induced by hypertonic dehydration and enhanced by absorbable alkali intake also could cause an increase of renal tubular reabsorption of calcium and a decrease of ionized calcium which might produce increased secretion of parathyroid hormone followed by vitamin D3 activation and increased Ca absorption from the gut. The metabolic alkalosis might be essential to the development of the milk-alkali syndrome without a high calcium and absorbable alkali intake.

Physiological and pathological effects of feeding high levels of magnesium to steers

The effects of feeding high levels of Mg were evaluated in a 130-d study with 24 steers. Six steers were allotted to each of four diets supplemented with MgO to attain .3, 1.4, 2.5 or 4.7% Mg, DM basis. Chromic oxide was used as digesta marker; fecal grab samples were collected once daily during nine consecutive 10-d periods. Steers fed 2.5 and 4.7% Mg refused some feed during the study, so their respective dietary Mg intakes were 2.4 and 3.7% (DM basis). Severe diarrhea and a lethargic appearance were observed in steers fed the two higher Mg levels. Fecal DM and apparent DM digestibility decreased linearly (P less than .01) with increased dietary Mg. Apparent Mg absorption (g/d) increased linearly (P les than .01) and apparent Ca and P absorption (g/d) decreased linearly (P less than .01) with addition of Mg to the diet. Increasing dietary Mg linearly elevated blood serum and erythrocyte Mg (P less than .01; P less than .05, respectively) and serum inorganic P (P less than .05) and linearly decreased serum Ca (P less than .01). Magnesium concentration in liver, kidney, skeletal muscle and rib-bone and P in skeletal muscle all increased linearly (P less than .05) with dietary Mg. Increasing dietary Mg in the steers caused a progressive degeneration of the stratified squamous epithelium of rumen papillae. A progressively more serious Mg toxicosis condition developed over time in steers fed diets containing 2.4 and 4.7% Mg.

A prospective randomized comparison of oral terbutaline and magnesium oxide for the maintenance of tocolysis

We compared oral magnesium oxide with oral terbutaline sulfate in a prospective, randomized manner to determine efficacy and side effects. Preterm labor patients whose labor was arrested with parenteral tocolysis were randomized to oral tocolysis with either magnesium oxide, 200 mg every 3 to 4 hours (n = 23), or terbutaline, 2.5 to 5 mg every 3 to 4 hours (n = 27). The number of patients who were delivered of infants before 36 weeks' gestation was similar between groups (18.5% receiving terbutaline versus 17.4% receiving magnesium). At least one side effect occurred in 81.5% of patients in the terbutaline group and 47.8% in the magnesium group (p less than 0.01). Finally, the cost for 1 day of magnesium (20 cents) is approximately one third the cost of terbutaline (56 cents). These data suggest that oral magnesium oxide is as effective as terbutaline for the maintenance of tocolysis, with fewer side effects and at a lower cost.

Effects of magnesium oxide on the lipid profile of healthy volunteers

Elevated serum cholesterol is a risk factor in the development of coronary artery disease. Magnesium has been reported to decrease total serum cholesterol, low density lipoprotein, and very low density lipoprotein, and increase high density lipoprotein. A randomized, double-blind, placebo-controlled, crossover study was completed to determine if supplemented magnesium, in the form of magnesium oxide, would produce changes in the lipid profile. Fifty normal volunteers received placebo or magnesium oxide, 400 mg capsules, twice a day for 60 days, then switched to the alternate treatment. Weight, height, blood pressure, serum potassium, serum magnesium, and a lipid profile were determined initially and after each treatment. Analysis of variance (ANOVA), comparing the mean of each component of the lipid profile at baseline and after each treatment, showed no significant difference. In conclusion, supplemental magnesium oxide did not produce statistically significant changes in the lipid profile in this group of healthy volunteers.

Pulmonary alveolar proteinosis and cement dust: a case report

Pulmonary alveolar proteinosis developed in a 29-year-old white man within 2 years of working as a cement truck driver. Pulmonary alveolar proteinosis (PAP), an uncommon respiratory disorder characterized by the accumulation of phospholipid material within the alveoli, has been described in association with exposure to silica, aluminum oxide, and a variety of dusts and fumes. Although a link between exposure to Portland cement and PAP has not been previously noted, this type of cement contains nearly 20% silica. Lung biopsy material, originally used to diagnose PAP, was reviewed under electron dispersive spectroscopy. Analysis indicated the presence of silica particles within the alveolar fluid and macrophages. A number of items support a causal relationship between exposure to cement dust and PAP: (1) the temporal sequence between assuming job duties and the development of the illness, (2) improvement following removal from further exposure, (3) dusty, unprotected working conditions, (4) the presence of silica within the cement, and (5) the alveolar fluid from periodic acid-Schiff-positive lung tissue.

Characterization of magnesium-induced urinary disease in the cat and comparison with feline urologic syndrome

Aggregates of struvite crystals caused urethral obstruction in a high percentage of cats fed moist and dry diets supplemented with Mg oxide. Some of the diets were associated with cystolith formation as well. The percentage of Mg in the experimental diets was a misleading indicator of Mg intake because of differences between moist and dry diets in their caloric density. Magnesium homeostasis was maintained in cats ingesting large quantities of Mg. Tissue (kidney, muscle, and rib) concentrations of Mg were the same in cats fed high Mg and control diets. Plasma Mg concentration was increased only in cats ingesting the largest amount of Mg. Magnesium homeostasis was maintained by a marked increase in urine Mg excretion. However, urine Mg concentration was not directly related to Mg intake, apparently because of differences between diets in intestinal absorption of Mg. Urethral obstruction of experimental cats was not associated with a transient increase in Mg intake, nor did obstructing cats have higher urine Mg concentrations than did nonobstructing cats fed the same diet. This observation indicates that factor(s) other than urine Mg concentration are important in urethral obstruction. Cats with urethral obstruction due to naturally occurring disease, feline urological syndrome (FUS), had markedly lower urine Mg concentrations than cats fed high Mg diets. This finding refutes the theory that cats develop FUS because of primary Mg hyperabsorptive phenomena or because of a primary urinary leak of Mg. It also indicates that factors other than urine Mg concentration are involved in the genesis of naturally occurring urethral obstruction. Another difference between the natural and the induced disease was related to the character of the urinary precipitates. Experimental diets higher in Mg concentration caused urolith formation, which is uncommon with FUS. Lower Mg diets caused obstruction with aggregates of crystals, but mucus was not observed. However, in the experimental disease induced in the present study, urinary precipitates were predominantly or exclusively struvite, as has been reported in the natural disease. Many similarities were seen between the diet-induced disease and FUS, but factors in addition to Mg intake are involved in the natural disease. The importance of Mg, compared with the undefined factors, remains to be established.

[Magnesium oxide as cause of metal fume fever]

Seven foundry workers are described who all developed pulmonary symptoms and in the majority of cases recurrent occupational fever; the onset of these episodes coincided with the introduction of a new founding technique resulting in exposure to magnesium oxide fumes. The foreman - most exposed because responsible for vaccination of the melted iron with metallic magnesium - developed disabling pneumopathy. The feverish episodes are interpreted as metal fume fever and in 6 patients the pneumopathy is considered to be due to alkalitoxic damage to the small airways and alveoli caused by the magnesium oxide fumes. The seventh patient suffered from allergic asthma bronchiale. Differentiation from hypersensitivity pneumonitis and from humidifier fever of nonallergic etiology is discussed.

Magnesium oxide induced metabolic alkalosis in cattle

A study was designed to compare the metabolic alkalosis produced in cattle from the use of an antacid (magnesium oxide) and a saline cathartic (magnesium sulphate). Six, mature, normal cattle were treated orally with a magnesium oxide (MgO) product and one week later given a comparable cathartic dose of magnesium sulphate (MgSO(4)). The mean percent dry matter content of the cattle feces changed significantly (P<0.001) following administration of both MgO (15.6-8.1) and MgSO(4) (17.0-8.7) but there was no significant difference between treatments. The mean rumen pH values changed significantly (P<0.001) following administration of both MgO (7.-8.7) and MgSO(4) (7.3-8.3) but there was no significant difference between treatments. However, use of the MgO product caused a more severe (P<0.001) metabolic alkalosis as determined by base excess values. The base excess values remained elevated for 24 hours in the MgO treated group compared to only 12 hours after MgSO(4) administration. Following MgO administration, mean hydrogen ion concentration (pH), bicarbonate ion concentration ([HCO(3)-]) and base excess were 7.44, 33.3 mmol/L and +8.0 respectively compared to 7.38, 27 mmol/L and +3.0 after MgSO(4). Since the oral use of MgO in normal cattle causes a greater and more prolonged metabolic alkalosis compared to MgSO(4), MgO is contraindicated as a cathartic in normal cattle or in cattle with abomasal abnormalities characterized by pyloric obstruction and metabolic alkalosis.

Fecal blood loss caused by two differently microencapsulated acetylsalicylic acid preparations in patients with rheumatoid arthritis. A prospective crossover study

In an investigator-blind crossover study, fecal blood loss determined by 51Cr-labelled red cells was measured in 17 male patients with rheumatoid arthritis and one with anchylosing spondylitis. In two periods, each of one week's duration and separated by a 3-week wash-out period, the patients received microencapsulated acetylsalicylic acid (ASA) 3 g daily--either iwht time-dependent (Acetard) or with pH-depeendent release (Reumyl). With the exception of one patient, who suffered clinically significant bleeding, both preparations produced only moderate bleeding. The bleeding provoked by ASA with pH-dependent release (median blood loss in ml/day: first period 1.6; last period 2.6) was less than with time-dependent release (first period 1.8; last period 3.5).

Influence of the sterilization method and of magnesium oxide on the tissue responses in the rat to modified starch glove powders

The tissue response to samples of a surgical glove powder was assessed from counts of the adhesions and granulomas found 7 and 14 days after introduction into the peritoneal cavity of rats, and by a histological study of affected tissues. Negative control groups treated with no powder and positive controls treated with talc were included. Various sample treatments were implemented to examine the effect of the sterilization method on the tissue response and the influence of magnesium oxide, normally added as a dispersing agent. The glove powder produced less reaction when steam-sterilized than when gamma-irradiated and the presence of magnesium oxide at 2% concentration made no detectable difference.

Gastrointestinal blood loss caused by controlled-release and conventional acetylsalicylic acid tablets

Gastrointestinal blood loss has been studied following oral administration of the novel controlled-release acetylsalicylic acid tablet preparation Acetard and the instant-release acetylsalicylic acid tablet Magnecyl (Ph. Nord. 63). Acetard contains micro-encapsulated acetylsalicylic acid crystals having an in vitro release time of approximately 4 hours. The investigation was carried out as a two-part, randomized cross-over trial, and with a test dosage of either 1 g X 4 or 2 g X 2 per day, given to 10 and 14 male students, respectively, during two 5-day periods separated by a one week interval. The dosage of the plain formulation was maintained at 1 g X 4 daily in both parts of the investigation. Faeces were collected every 24 hours throughout the trial, covering a total of 4 weeks. Blood loss was measured using the 51Cr labelling technique. Acetard was found to cause statistically significantly less gastrointestinal blood loss as compared with the plain formulation, irrespective of whether Acetard was given twice or four times a day.

Alkalosis and seizure due to a cation-exchange resin and magnesium hydroxide

A patient with chronic renal failure received sodium polystyrene sulfonate and magnesium hydroxide for the treatment of hyperkalemia. This combination therapy produced a severe metabolic alkalosis which, in the presence of the patient's chronic hypocalcemia, precipitated a grand mal seizure.

Hypokalemia and metabolic alkalosis resulting from overuse of magnesium oxide

A 23 year old woman had taken large doses of magnesium oxide (up to 20 to 30g per day) initially for habitual constipation and later for idiopathic edema instead of diuretics, until the concealed abuse was discovered. During the abuse she showed hypokalemia and metabolic alkalosis. When the ingestion was stopped, the electrolyte imbalance recovered within two weeks.