Potential uses for metoclopramide

Sustained release microspheres of metoclopramide using poly(D,L-lactide-co-glycolide) copolymers

Metoclopramide was encapsulated with poly(D,L-lactide co glycolide) copolymers of different molecular weights using the emulsification/solvent evaporation technique. These polymers included poly(D,L-lactide-co-glycolide) 50:50 with inherent viscosity (i.v.) 0.2, and average molecular weight 8000, poly(D,L-lactide-co-glycolide) 50:50 with i.v. 0.8 and average molecular weight 98000 and poly(D,L-lactide-co-glycolide) 85:15 with i.v. 1.4 and average molecular weight 220000. The effect of the polymers' molecular weights as well as the polymer-to-drug ratios on the yield, the particle size distribution, and the drug content of the microspheres was investigated. The release rate of the drug was studied for 96 h in a phosphate buffer of pH 7.4. The study also investigated the effect of the new poly(lactide-co-glycolide)-H series on the characteristics of the prepared microspheres. Data revealed that a higher yield was obtained with polymers of lower molecular weights. A lower yield was also obtained with increasing the drug-to-polymer ratios for all the investigated polymers. The drug content of the microspheres was lower than expected, ranging from 49-85%, which suggested a chemical interaction between the drug and the polymers, as proved by differential scanning calorimetry (DSC) and infra red (IR) studies. A higher interaction was obtained with the H-series of the copolymers. The release of the drug mainly followed zero order kinetics on increasing either the polymers' molecular weights or the polymer-to-drug ratios. Diffusion kinetics was observed only with those batches prepared with low polymer-to-drug ratios. The release rate was a function of both the polymers' molecular weights and the drug-to-polymer ratios.

Orphan neurones and amine excess: the functional neuropathology of Parkinsonism and neuropsychiatric disease

The aetiology and treatment of Parkinsonism is currently conceptualised within a dopamine (DA) deficiency-repletion framework. Loss of striatal DA is thought to cause motor impairment of which tremor, bradykinaesia and rigidity are prominent features. Repletion of deficient DA should at least minimise parkinsonian signs and symptoms. In Section 2, based on extensive pre-clinical and clinical findings, the instability of this approach to Parkinsonism is scrutinised as the existing negative findings challenging the DA deficiency hypothesis are reviewed and reinterpreted. In Section 3 it is suggested that Parkinsonism is due to a DA excess far from the striatum in the area of the posterior lateral hypothalamus (PLH) and the substantia nigra (SN). This unique area, around the diencephalon/mesencephalon border (DCMCB), is packed with many ascending and descending fibres which undergo functional transformation during degeneration, collectively labelled 'orphan neurones'. These malformed cells remain functional resulting in pathological release of transmitter and perpetual neurotoxicity. Orphan neurone formation is commonly observed in the PLH of animals and in man exhibiting Parkinsonism. The mechanism by which orphan neurones impair motor function is analogous to that seen in the diseased human heart. From this perspective, to conceptualise orphan neurones at the DCMCB as 'Time bombs in the brain' is neither fanciful nor unrealistic [E.M. Stricker, M.J. Zigmond, Comments on effects of nigro-striatal dopamine lesions, Appetite 5 (1984) 266-267] as the DA excess phenomenon demands a different therapeutic approach for the management of Parkinsonism. In Section 4 the focus is on this novel concept of treatment strategies by concentrating on non-invasive, pharmacological and surgical modification of functional orphan neurones as they affect adjacent systems. The Orphan neurone/DA excess hypothesis permits a more comprehensive and defendable interpretation of the interrelationship between Parkinsonism and schizophrenia and other related disorders.

Determination of metoclopramide and two of its metabolites using a sensitive and selective gas chromatographic-mass spectrometric assay

A modified gas chromatographic-mass spectrometric (GC-MS) assay has been developed to quantitate metoclopramide (MCP) and two of its metabolites [monodeethylated-MCP (mdMCP), dideethylated-MCP (ddMCP)] in the plasma, bile and urine of sheep. The heptafluorobutyryl derivatives of the compounds were formed and quantitated using electron-impact ionization in the selected-ion monitoring mode (MCP, m/z 86, 380; mdMCP, m/z 380 and ddMCP, m/z 380). No interference was observed from endogenous compounds following the extraction of various biological fluids obtained from non-pregnant sheep. Sample preparation has been simplified and the method is more selective and sensitive (2 fold) than our previous assay using electron-capture detection. The limit of quantitation for MCP, mdMCP and ddMCP was 1 ng/ml in plasma, urine and bile, requiring 0.5 ml of sample. This represents 2.5 pg of the analytes at the detector. The standard curves were linear over a working range of 1-40 ng/ml. Absolute recoveries in plasma ranged from 76.5-94.7%, 79.2-96.8%, 80.3-102.2% for MCP, mdMCP and ddMCP, respectively. In urine, recoveries ranged from 56.5-87.8%, 61.5-87.5%, 62.6-90.2% for MCP, mdMCP and ddMCP, respectively. Recoveries in bile ranged from 83.5-100.9%, 78.5-90.5%, 66.9-79.2% for MCP, mdMCP and ddMCP, respectively. Overall intra-day precision ranged from 2.9% for MCP in plasma to 12.6% for mdMCP in bile. Overall inter-day precision ranged from 5.9% for MCP in urine to 14.9% for ddMCP in bile. Bias was the greatest at the 1 ng/ml concentration in all biological fluids ranging from a low of 2.4% for mdMCP in plasma to a high of 11.9% for ddMCP in urine. Applicability of the assay for pharmacokinetic studies of MCP, mdMCP and ddMCP in the plasma and urine of a non-pregnant ewe is demonstrated.

Lactational failure--study of risk factors in Turkish mothers

Risk factors for lactational failure in puerperium were investigated. Sixty mothers with inadequate daily milk supply for their babies were the lactational failure group, and 60 mothers with similar age having babies with similar age and weight were chosen as the control group. Low prolactin levels, low serum iron and low serum ferritin levels and low aldosterone values and birth in community hospitals were associated with significantly increased risk of deficient lactation. High income of the family, increase osmolality of breastmilk, high systolic blood pressure of the mother, birth by cesarean section were some of the variables that increased the risk that could not reach the level of significance. Prematurity of the baby was not among the risk factors if the gestational ages were more than 30 weeks. It is concluded that physicians awareness of the factors that may adversely effect the initiation and continuation of lactation is vital. Correcting iron deficiency even if it is not overt, sparing more time for the mothers discussing the benefits of breastmilk to their babies, and avoiding cesarean section if possible may help increase the incidence of breastmilk feeding.

Persistent postoperative hiccups: a review

The pathogenesis of persistent postoperative hiccups is not known. Hiccups can present as a symptom of a subphrenic abscess of gastric distention, and metabolic alterations may also cause hiccups. The hiccups may develop because of increased activity in neural reflex pathways not yet fully defined. Numerous treatment modalities have been tried but with questionable success. Valproate has proven effective in two trials investigating persistent non-surgical hiccups. The simple application of a nasogastric tube may successfully treat the hiccups, possibly because of an alteration of the activity in the reflex neural pathways involved. The available literature on the treatment of persistent hiccups is reviewed, and a treatment protocol for persistent postoperative hiccups is provided.

Lidocaine pretreatment effectively decreases the incidence of hiccups during methohexitone administration for dilatation and curettage

The efficacy of lidocaine 1 mg.kg-1 for prevention of methohexitone-induced hiccups was assessed in a double-blind fashion in 200 patients undergoing dilatation and curettage for pregnancy interruption. The patients were randomly assigned to receive either lidocaine 1% or saline 0.9% in a similar way (1 ml for every 10 kg of body weight). The incidence of hiccups was 16% in the control group compared to 6% in the lidocaine group. We speculate that this reduction in the methohexitone-induced hiccup ratio is related to lidocaine's membrane-stabilizing properties, which decrease the excitability of all the nervous structures involved in this reflex.

Metoclopramide: an analysis of inappropriate long-term use in the elderly

OBJECTIVE

To present a case of possible metoclopramide-induced tardive dyskinesia and document the frequent use of metoclopramide for inappropriate lengths of treatment in elderly, ambulatory subjects.

DESIGN

Descriptive study that identified long-term users of metoclopramide among a population of 4515 elderly subjects.

SETTING

Participants in an ambulatory health-screening program in Florida (Florida Geriatric Research Program).

PARTICIPANTS

Individuals (2898 women and 1617 men) over the age of 65 years who volunteered for annual health screening.

INTERVENTIONS

All medication histories for participants were reviewed to identify subjects who reported metoclopramide use on at least one visit to the program.

RESULTS

Thirty-four participants (0.75 percent) reported the use of metoclopramide during at least one visit. Eleven subjects (32.4 percent) reported that they had used this drug for longer than one year. Nine of the 34 subjects (26.5 percent) also reported the use of metoclopramide at their next annual visit.

CONCLUSIONS

Results from this study suggest that metoclopramide is frequently prescribed inappropriately to treat gastrointestinal disorders. Long-term use of this drug exposes patients to an unnecessary risk of adverse drug reactions.

Premedication with metoclopramide decreases the frequency of methohexital induced hiccup

Metoclopramide is one of many drugs that have been recommended for the treatment of intractable hiccup. Methohexital may produce hiccup during induction of general anesthesia. 211 women received methohexital for induction and maintenance of general anesthesia for short gynaecological procedures. All the patients were premedicated with fentanyl, diazepam and atropine. 109 patients were randomly selected to receive metoclopramide before induction of anesthesia; the remaining 102 patients served as a control group, and were anesthetized without metoclopramide premedication. The frequency of hiccup was compared between the two groups. 7 patients had hiccup in the metoclopramide premedicated group, as compared to 17 patients in the control group. This difference was statistically significant. We conclude that metoclopramide reduces the frequency of methohexital induced hiccup, and recommend that metoclopramide be routinely used for the premedication of methohexital injection.

Hiccups (singultus): review and approach to management

Hiccups are a common, and fortunately usually transient, benign malady. Occasionally, however, hiccups fail to resolve spontaneously, resulting in patient fatigue and incapacitation and the need for the affected individual to seek medical care for resolution of the problem. The approach to the management of these patients consists of the identification and treatment of serious underlying causes of the episode as well as therapeutic interventions to achieve hiccup resolution.

Metoclopramide potentiates d-amphetamine-induced hypermotility and stereotypy in rat

The substituted benzamide metoclopramide has been reported to block the behavioral effects of dopamine agonists, whereas its congener sulpiride potentiates these effects. We injected metoclopramide 2.0, 4.0, or 8.0 mg/kg PO into rats 2 hr before d-amphetamine 1.5 mg/kg IP and measured locomotion for 3 hr. We injected metoclopramide 8.0 mg/kg PO into rats 2 hr before d-amphetamine 1.5, 3.0, or 6.0 mg/kg IP and measured stereotypy for 3 hr. Metoclopramide potentiated the effects of all doses of d-amphetamine on both measures; peak effects occurred in the second or third hr after d-amphetamine injection. Metoclopramide alone tended to reduce behavior. The results suggest that metoclopramide is qualitatively similar to sulpiride in its interaction with d-amphetamine, and that metoclopramide's mechanism of action is not a simple dopaminergic antagonism. Clinicians are advised that metoclopramide, which is presently extensively for gastrointestinal and other disorders, may interact adversely with drugs that affect dopaminergic function.