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Biomedical subjects

P H Jansen

Publications and source records attributed to P H Jansen.

At least 19 recordsLinked to original sources
PubMed2000

Hydroquinine pharmacokinetics after oral administration in adult patients with muscle cramps.

OBJECTIVE: This study was conducted to determine the pharmacokinetic properties of hydroquinine after oral administration in adult patients with muscle cramps. The main reason for this study was the poor availability of pharmacokinetic data, hindering the design of studies to explore the possible relationship between hydroquinine concentrations and effects. METHODS: Sixteen adult patients with a clinical history of muscle cramps were given once-daily oral doses of 300 mg hydroquinine hydrobromide for 4 days. Serum and saliva samples were taken following a predefined schedule until 24 h after the last dose. Urine was collected during the study period. Hydroquinine concentrations were measured, and calculations were made of pharmacokinetic parameters using non-linear curve fitting. RESULTS: Pharmacokinetics of hydroquinine could be best described using a one-compartment open model. After oral administration, hydroquinine was rapidly absorbed (mean +/- SD: maximum concentration 2.43+/-0.68 mg/ 1; time to maximum concentration 1.4+/-1.2 h; lag time 0.54+/-0.50 h). With an elimination half-life of 10.9+/-6.1 h, steady-state was reached in several days. The distribution volume was 1.24+/-0.29 l/kg, total clearance was 6.7+/-3.2 l/h. The measured unbound hydroquinine fraction was 8.6+/-3.0%. No correlation was found between saliva and serum concentrations. Cumulative urinary excretion of unchanged hydroquinine 24 h after the first dose was 35.5+/-9.2 mg. CONCLUSION: Pharmacokinetic properties of hydroquinine are roughly similar to those of quinine. The unchanged fraction of hydroquinine excreted in urine is higher than that reported for quinine. Saliva hydroquinine concentrations could not be related to serum values. Steady-state trough or other fixed-time serum concentrations may prove useful for further optimisation of hydroquinine dosage.

Administration, Oral↗
PubMed1999

Past and current understanding of the pathophysiology of muscle cramps: why treatment of varicose veins does not relieve leg cramps.

Historically relevant hypotheses on the pathophysiology of muscle cramps are reviewed. Psychosomatic, static, vascular, myogenic and neural theories are highlighted from a clinician's point of view. Modern neurophysiologic research leaves little doubt that muscle cramp is caused by excitation of spinal motor neurones mediated by changes in presynaptic input. Nevertheless, obsolete theories and relative treatments stubbornly persist in clinical practice.

Humans↗
PubMed1997

Randomised controlled trial of hydroquinine in muscle cramps.

BACKGROUND: Although quinine and hydroquinine are commonly prescribed for muscle cramps, controlled clinical trials of these drugs have reported mixed findings about efficacy. We investigated hydroquinine therapy in otherwise healthy adults who had frequent, ordinary muscle cramps. METHODS: This randomised, double-blind, placebo-controlled, parallel-group trial consisted of three consecutive 2-week periods: qualification, treatment, and washout, 68 women and 44 men who had at least three muscle cramps per week were enrolled. During the treatment period, participants were randomly assigned 300 mg daily dose of hydroquinine hydrobromide dihydrate (54 participants) or placebo (58). The frequency, severity (1-10), duration, and location of muscle cramps, as well as any side-effects, were recorded by participant in daily diaries. The primary outcome measures were the number of muscle cramps and the number of days during which the participants had muscle cramps (cramp-days). FINDINGS: We excluded five participants from both groups from the analysis. Thus, data from 49 hydroquinine-group participants and 53 placebo-group participants were analysed. In both groups the total number of muscle cramps and the number of cramp-days decreased during the treatment period compared with the qualification period. However, these improvements were greater in the hydroquinine group than in the placebo group. The hydroquinine-group participants reported a median of 8 (95% CI 7-12) fewer cramps and median of 3 (1-4) fewer cramp-days, whereas those on placebo reported only 3 (0-5) fewer cramps and 1 (0-5) fewer cramp-days. 32 (65%) of participants in the hydroquinine group had a 50% or greater reduction in the number of muscle cramps. After the onset of cramps, hydroquinine did not reduce the severity or duration of cramps. We also found a sustained effect after treatment had stopped. Hydroquinine was well tolerated, and resulted in only mild side-effects. INTERPRETATION: In our study, 300 mg hydroquinine was safe to take in the short-term and significantly more effective than placebo in the prevention of frequent, ordinary muscle cramps. This therapeutic effect outlasted the duration of treatment.

Administration, Oral↗
PubMed1996

Leber's hereditary optic neuropathy with the 11 778 mtDNA mutation and white matter disease resembling multiple sclerosis: clinical, MRI and MRS findings.

A mother and her son are reported who suffer from Leber's hereditary optic neuropathy (LHON) with the 11778 mtDNA mutation. In both subjects additional clinical and paraclinical evidence of a cerebral demyelinating disease was found. This combination has been reported incidentally in females, rarely in males. Magnetic resonance imaging and proton spectroscopy findings are reported. These findings are compatible with multiple sclerosis.

Adult↗
PubMed1996

Atypical transient ischemic attacks in thrombocythemia of various myeloproliferative disorders.

Neurological symptoms of transient unsteadiness, dysarthria, dysphasia, dysbasia, transient monoor hemiparesis, hemiparesis, scintillating scotomas, amaurosis fugax, vertigo, dizziness, migraine accompaniments, syncope and seizures were the presenting manifestations of thrombocythemia in various myeloproliferative disorders. Erythromelalgia preceded or followed the neurologic ischemic attacks. The neurologic and ocular attacks usually had a sudden onset, lasted for a few seconds to several minutes and occurred independently or sequentially rather than simultaneously. This clinical syndrome is caused by platelet-mediated ischemic and thrombotic processes in the end-arterial microvasculature and reflects the existence of a platelet dependent and aspirin responsive arterial thrombophilia in thrombocythemia as novel disease entity, which confirms and elucidates Mitchell's hypothesis.

Adult↗
PubMed1994

Efficacy of hydroquinine in preventing frequent ordinary muscle cramp outlasts actual administration.

In order to compare the efficacy of a daily dose of 300 mg hydroquinine hydrobromide and placebo in preventing frequent ordinary muscle cramp, we designed a randomized, double-blind, placebo-controlled study of three consecutive 2-week periods viz. a qualification period, a medication period and a wash-out period. Twenty healthy adult volunteers experiencing at least 3 muscle cramps a week (6 men, 14 women aged 38-78 yrs) were enrolled into this study, and 19 of them completed it. Hydroquinine hydrobromide (300 mg/day) was administered to group 1 (10 women) and placebo to group 2 (4 women, 6 men). The frequency, severity, duration and location of muscle cramps as well as short-term adverse drug effects were recorded in daily diaries. Compared with placebo the decrease in the mean number of muscle cramps (16.1 or 58%) in the active drug treatment group during the medication period was highly significant (Wilcoxon test p = 0.004). During the wash-out period this decrease partly persisted (8.9 or 33%). In this study a daily dose of 300 mg hydroquinine hydrobromide was effective in preventing frequent ordinary muscle cramp in healthy female volunteers. The effects of hydroquinine outlasted its administration. The drug was well tolerated.

Adult↗
PubMed1991

Estimation of the frequency of the muscular pain-fasciculation syndrome and the muscular cramp-fasciculation syndrome in the adult population.

A nationwide two-phase survey was carried out of the adult population of the Netherlands regarding fasciculation, muscle pain and muscle cramp. We conducted a population-based telephone interview with 780 Dutch adults, followed by a questionnaire covering more clinical details, filled out by 311 subjects, who had been interviewed by telephone previously. From these data the frequencies of fasciculation (men 50%, women 61%), muscle cramp (men 28%, women 42%) and muscle pain (men 48%, women 60%) in the Dutch adult population in 1988 were estimated. The combined occurrence of frequent fasciculation and frequent muscle cramp as well as of frequent fasciculation and frequent muscle pain was reported only sporadically. Although the muscular pain-fasciculation syndrome and the muscular cramp-fasciculation syndrome represent combinations of common neuromuscular phenomena, their occurrence in the general population proved to be rare. This finding supports their clinical identity as distinct motor unit hyperactivity syndromes rather than mere coincidences of fasciculation, muscle cramp and muscle pain.

Adult↗
PubMed1990

Muscle cramp: main theories as to aetiology.

Historically relevant hypotheses on the pathophysiology of muscle cramp are reviewed. Psychosomatic, static, vascular, myogenic and neural theories are highlighted from a clinician's point of view. Modern neurophysiological research leaves little doubt that true muscle cramp is caused by explosive hyperactivity of motor nerves. Several mechanisms may be involved including spinal disinhibition, abnormal excitability of motor nerve terminals and spreading of muscle contraction by ephaptic transmission or axon reflexes.

Diagnosis, Differential↗
PubMed1990

Persistent periodic hiccups following brain abscess: a case report.

A case is reported of a patient with periodic persistent hiccups and secondary generalised epilepsy lasting for a period of five years following a right temporal brain abscess. The recurring episodes of hiccups had a ten day rhythmicity and unlike epileptic convulsions were unresponsive to treatment.

Adult↗
PubMed1988

Hypomanic behaviour associated with familial spastic paraplegia.

Psychiatric manifestations of familial spastic paraplegia are rare and have been described only infrequently. A 35-year-old male is reported, who presented both hypomanic behaviour and gait disturbances as features of a previously undiagnosed familial spastic paraplegia. This association implies that the CNS manifestations of familial spastic paraplegia may overlap with the neurochemical or neuroanatomic substrata regulating mood.

Adult↗
PubMed1987

Effect of thymectomy on myasthenia gravis and autoimmune thrombocytopenic purpura in a 13-year-old girl.

We report the association of myasthenia gravis (MG) and autoimmune thrombocytopenic purpura (AITP) in a 13-year-old girl. The co-existence of these autoimmune diseases is rare in adults and, to our knowledge, never described in children. In our patient thymectomy had a therapeutic effect on both MG and AITP, suggesting a altered T-cell function as a pathogenic factor of major importance in both affections.

Adolescent↗
PubMed1987

Mannosidosis: a study of two patients, presenting clinical heterogeneity.

Two unrelated patients suffering from mannosidosis, aged 9 and 33 years, are reported, presenting two extremes in the phenotypic expression of this lysosomal storage disorder. Clinical, radiological, biochemical and therapeutical aspects of the disease are discussed. Our patients support the concept that mannosidosis is not a homogeneous syndrome but manifests wide clinical heterogeneity.

Adult↗