Methyldopa and propranolol or practolol in moderate hypertension.

The effect of a low dose of methyldopa combined with (a) a non-selective and (b) a selective beta-adrenoceptor antagonist was studied in a double-blind crossover trial in 24 carefully selected patients with moderate hypertension (mean initial lying blood pressure 189/117 mm Hg). Each patient received methyldopa 750 mg/day, propranolol 240 mg/day, practolol 600 mg/day, methyldopa 750 mg/day combined with propranolol 240 mg/day, methyldopa 750 mg/day combined with practolol 600 mg/day, and placebo for four weeks each according to a random sequence. After four weeks of therapy the most effective treatment, methyldopa combined with propranolol, reduced lying and standing blood pressures by 36-5/21-4 mm Hg and 44-7/25 mm Hg respectively. Thic combination had similar effects to those of the combination of methyldopa with the cardioselective agent practolol except that it reduced lying diastolic pressure further. The combination was more effective than either treatment alone. No significant differences were found between the effects of propranolol, practolol, or methyldopa at the doses used.     

Effects of methyldopa on prolactin and growth hormone.

The effects of administration of methyldopa on serum prolactin and growth hormone (GH) concentrations in hypertensive patients were studied. Single doses of methyldopa (750 or 1000 mg) significantly increased serum prolactin levels, peak concentrations occurring four to six hours after drug administrations. Long-term methyldopa treatment was associated with threefold to fourfold increases in basal prolactin levels compared with those in normal subjects. In patients treated with methyldopa for two to three weeks the GH response to insulin hypoglycaemia was significantly greater than in normal subjects and untreated hypertensive patients. In contrast, patients treated for prolonged periods (mean 13-4 months) had a GH reponse indistinguishable from normal.     

Methyldopa Liver Damage

Twenty patients are described in whom liver damage appeared to be directly related to the administration of methyldopa. Sixteen had hepatitic syndromes from which they recovered on stopping methyldopa; four of these patients had recurrences of jaundice after a second course of the drug. Features suggestive of active chronic hepatitis were found in two patients. There were two deaths attributed to methyldopa, one of these being in a patient with pre-existing undiagnosed macronodular cirrhosis.     

A Within-patient Comparison of Debrisoquine and Methyldopa in Hypertension

In a titrated dose cross-over trial of debrisoquine and methyldopa in 38 hypertensive patients neither drug was superior in lowering supine or standing diastolic pressure with a minimum of side effects. Methyldopa caused significantly greater reduction of supine (P<0·001) and standing (P<0·02) systolic pressure but caused intolerable side effects in two patients. Tiredness was the most characteristic and troublesome side effect with methyldopa and postural hypotension was prominent in patients while on debrisoquine.     

Atenolol,methyldopa, and chlorthalidone in moderate hypertension.

Combined treatment with low doses of different drugs is widely used for moderate hypertension. The effects of atenolol and methyldopa at two dose levels and in combination at the lower doses were studied in patients with moderate hypertension on continuous treatment with moderate hypertension on continuous treatment with chlorthalidone. The mean reduction in standing blood pressures obtained with atenolol 150 and 300 mg/day was about 27/17 mm Hg and with methyldopa 750 and 1500 mg/day about 28/14 mm Hg. Combined treatment with atenolol 150 mg/day and methyldopa 750 mg/day for four weeks resulted in a reduction of 38/25 mm Hg. No difference was observed between the two doses of methyldopa. The lower dose of atenolol was better than the lower dose of methyldopa in reducing lying and standing diastolic blood pressures. These findings show that in patients on continuous treatment with chlorthalidone the addition of atenolol alone or methyldopa alone or of atenolol and methyldopa in combination is effective in the treatment of moderate hypertension.     

Effect of methyldopa treatment on cardiac function and myocardial blood flow in mongrel dogs.

Administration of methyldopa (100 mg/kg, orally twice daily for a period of 3 days) to mongrel dogs produced significant reductions in blood pressure and heart rate. The hypotensive effect of the drug was due to a reduction in peripheral resistance. Methyldopa treatment also produced a significant decrease in coronary vascular resistance. Studies on the left ventricular function indicated that treatment with methyldopa does not compromise the ability of the myocardium to respond to an increased work load. Thus, the beneficial effect of this agent on the myocardial circulation, together with its lack of any detrimental effect on the cardiac function suggest that methyldopa may be an effective agent for the control of hypertension.     

Levodopa in Parkinsonism: the Effects of Withdrawal of Anticholinergic Drugs

The results are reported of a trial in which 34 patients receiving a stable dose of levodopa for the treatment of idiopathic Parkinsonism, as well as anticholinergic drugs which they had been taking before the introduction of levodopa, underwent withdrawal of their anticholinergic remedies. Withdrawal was gradual over four weeks in 17 patients (group 1) and abrupt in the remaining 17 (group 2).Only 11 out of 34 patients on stable levodopa therapy were able to tolerate withdrawal of anticholinergic drugs for more than eight weeks. The main reasons for the resumption of these remedies were subjective increases in slowness in 20 (59%), tremor in 15 (44%), and recurrence of hypersalivation in 5 (15%). Hypersalivation was the single feature which was most significantly and adversely influenced by anticholinergic withdrawal in patients on levodopa irrespective of whether withdrawal was sudden or gradual. It is suggested that the synergism which seems to exist between anticholinergic remedies and levodopa may be due to inhibition of dopamine inactivation by anticholinergic drugs, thus ensuring continual utilization, or alternatively, to a primary central anticholinergic effect.Objective and more severe subjective deterioration occurred only on sudden withdrawal. Hence we would advise that if for any reason anticholinergic drugs are to be withdrawn in patients receiving a stable dosage of levodopa this must be done slowly. Conversely it would appear from our results that the introduction of anticholinergic drugs in patients treated initially with levodopa is likely to produce additional benefit, particularly when the maximum tolerated dose of levodopa is small.     

Enhancement of Methyldopa Metabolism with Barbiturate

The spurious increase in serum catecholamine levels associated with methyldopa treatment can be reduced by the simultaneous administration of phenobarbitone. This accelerating effect of phenobarbitone on methyldopa metabolism has been demonstrated in relation to both adrenaline and noradrenaline, and investigations suggest that it is due to the effect of barbiturate on the activity of metabolizing enzymes.     

The Long-Term Effectiveness of Methyldopa in Hypertension

A trial of methyldopa in hypertension was conducted in 60 patients for a mean time of 9.4 months. Initially, four different dosages of methyldopa were studied and blood pressure was significantly lowered in the supine and standing positions. Standing blood pressure was significantly reduced more than supine. An average of 5.2 visits passed before maintenance blood pressure was obtained. There was no significent evidence of deterioration during the duration of this study. Side effects were mild. Only two patients voluntarily requested discontinuance of this study. Tolerance to the drug occurred and approximately 50 per cent of the patients no longer had a significant blood pressure reduction to methyldopa alone by the end of the study. Methyldopa appears to be a significant addition to the drug therapy of hypertension.     

Characterization of alpha-adrenoceptors involved in central thermoregulation in rabbits

Intracerebroventricular (icv) injection of methyldopa induced body temperature changes in the rabbits. The dose of 100 micrograms/kg did not produce any significant change on body temperature whereas 250 micrograms/kg of the drug induced hyperthermia. Higher dose of 500 micrograms/kg produced initial hypothermia which was followed by hyperthermia. On further increase of the dose to 1 mg/kg, consistent hypothermia was evident. Prazosin, a specific post-synaptic alpha 1 adrenoceptor blocker, induced hypothermia whereas piperoxan (presynaptic alpha 2 antagonist) produced hyperthermia. The pretreatment with prazosin, blocked the hyperthermic response of methyldopa. The initial hypothermia by 500 micrograms/kg of methyldopa was also potentiated. The pretreatment with piperoxan completely blocked the hypothermia but had no effect on hyperthermic response of methyldopa. Pretreatment of rabbits with both prazosin and piperoxan completely blocked the hypothermia as well as hyperthermic response of methyldopa. Thus it appeared that both presynaptic alpha 2 and postsynaptic alpha 1 adrenoceptors are involved in central thermoregulation in rabbits.     

Randomised controlled comparative study of methyldopa and oxprenolol in treatment of hypertension in pregnancy.

One hundred pregnant women with hypertension (defined as diastolic blood pressure at or above 95 mm Hg) were allocated at random to treatment with methyldopa or oxprenolol and were compared with nonhypertensive controls matched according to parity and gestation at delivery. The patients were also stratified into those entering the study early (before 32 weeks'' gestation) and those entering late (after 32 weeks'' gestation). Although there were no differences in diastolic blood pressure between the hypertensive groups before or during treatment, in the early entry group the systolic blood pressure at entry of those allocated to oxprenolol was significantly higher than that of those receiving methyldopa; this difference remained throughout the treatment period. Also in the early entry group further increments of drug treatment were required to control blood pressure of patients receiving oxprenolol than in those receiving methyldopa. The eventual fetal outcome for all patients treated with methyldopa was the same as that for those treated with oxprenolol; birth weight, placental weight, head circumference, and Apgar score were not significantly different and there were no stillbirths in either group.     

Asymmetrical Effect of Levodopa on the Neural Activity of Motor Regions in PD

Parkinson''s disease (PD) is a neurodegenerative illness often characterized by asymmetrical symptoms. However, the reason for this asymmetry and the cerebral correlates underlying symptom asymmetry are still not well understood. Furthermore, the effects of levodopa on the cerebral correlates of disease asymmetry have not been investigated. In this study, right-handed PD patients performed self-initiated, externally triggered and repetitive control finger movements with both their right and left hands during functional magnetic resonance imaging (fMRI) to investigate asymmetrical effects of levodopa on the hemodynamic correlates of finger movements. Patients completed two experimental sessions OFF and ON medication after a minimum of 12 hours medication withdrawal. We compared the effect of levodopa on the neural activation patterns underlying the execution of both the more affected and less affected hand for self-initiated and externally triggered movements. Our results show that levodopa led to larger differences in cerebral activity for movements of the more affected, left side: there were significant differences in activity after levodopa administration in regions of the motor cortico-striatal network when patients performed self-initiated and externally triggered movements with their left hand. By contrast, when patients used their right hand, levodopa led to differences in cerebellar activity only. As our patients were affected more severely on their left side, we propose that levodopa may help provide additional dopaminergic input, improving movements for the more severely affected side. These results suggest that the impact of reduced dopamine in the cortico-striatal system and the action of levodopa is not symmetrical.     

Antinuclear antibodies in patients receiving non-practolol beta-blockers.

Antinuclear antibodies (ANA) were found in 54 (7.0%) out of 767 treated hypertensive patients compared with 59 (2.4%) out of 2470 healthy controls. Inclusion of a non-practolol beta-blocker in the treatment regimen did not significantly affect the incidence of ANA. ANA was found in significantly more patients being treated with methyldopa (13.0%) than patients receiving other hypotensive agents (3.8%). Non-practolol beta-blockers in combination with methyldopa did not increase the incidence of ANA further.     

Attenuation of levodopa-induced dyskinesia by normalizing dopamine D3 receptor function

In monkeys rendered parkinsonian with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), expression of the dopamine D3 receptor was decreased. However, levodopa-induced dyskinesia (LID), similar to the debilitating and pharmacoresistant involuntary movements elicited after long-term treatment with levodopa in patients with Parkinson disease (PD), was associated with overexpression of this receptor. Administration of a D3 receptor-selective partial agonist strongly attenuated levodopa-induced dyskinesia, but left unaffected the therapeutic effect of levodopa. In contrast, attenuation of dyskinesia by D3 receptor antagonists was accompanied by the reappearance of PD-like symptoms. These results indicated that the D3 receptor participated in both dyskinesia and the therapeutic action of levodopa, and that partial agonists may normalize D3 receptor function and correct side effects of levodopa therapy in patients with PD.     

Long-term therapy of Parkinson's disease with amantadine,alone and combined with levodopa

A dual study was conducted to assess (1) the long-term antiparkinsonian action of amantadine without levodopa and (2) the advantage of combined amantadine and levodopa over single-drug therapy, including changes in symptom severity when placebo replaces amantadine but levodopa is maintained.Good to excellent results were obtained in 25% of the total pool of 77 patients on amantadine. No decline in therapeutic effect took place during a mean follow-up of 21 months.Thirty-seven patients with considerable residual deficit after single-drug therapy derived improvement from the second drug (levodopa or amantadine). Gains in neurological signs and activities of daily living (ADL) ranged between 50 and 60% and for timed skills close to 25%. Depending on the individual indices, between 64 and 100% of patients improved with the second drug.Placebo instead of amantadine produced deterioration. There was 75% loss in ADL, 45% loss in timed skills and losses in neurological signs exceeded gains produced by two-drug therapy.     

Hypotensive Action and Side Effects of Clonidine-Chlorthalidone and Methyldopa-Chlorthalidone in Treatment of Hypertension

In an open, randomized, cross-over study the hypotensive action and side effects of clonidine-chlorthalidone and methyldopa-chlorthalidone combinations were compared. The diastolic morning blood pressure could be reduced to 95 mm. Hg or below in significantly more patients with clonidine than with methyldopa. Side effects, however, were more commonly encountered during the clonidine than during the methyldopa phase.     

Randomised comparison of methyldopa and oxprenolol for treatment of hypertension in pregnancy.

Fifty-three pregnant women with moderately severe hypertension were randomly allocated to treatment with methyldopa or oxprenolol. There were no significant differences between the groups in age, height, weight, parity, or stage of gestation at the start of treatment. The outcome of pregnancy was better in the group treated with oxprenolol, with greater maternal plasma volume expansion and placental and fetal growth. No intrauterine deaths occurred in either group, and antepartum fetal distress, detected by oxytocin challenge testing, was evident in only one patient, who received methyldopa. This infant, and one other in the methyldopa group, died in the neonatal period. No neonatal deaths occurred in the oxprenolol-treated group. Even in this small number of patients these results were considerably better than those in untreated women with hypertension of similar severity. Apgar scores in both groups were equivalent at birth, while blood sugar concentrations were higher in the oxprenolol group. Oxprenolol appears to be safe and effective in controlling hypertension during pregnancy. There was no evidence of harmful effects on the fetus, and oxprenolol may offer a selective advantage over methyldopa for fetal growth and wellbeing in utero.     

Treatment of Hypertension with Propranolol

When used in the treatment of hypertension propranolol is at least of similar potency to bethanidine, guanethidine, and methyldopa. Propranolol does not produce postural or exercise hypotension and it seems that it is often more acceptable to patients than conventional drugs. It usually produces the best control of the supine blood pressure.A series of 109 hypertensive patients was treated with propranolol; in nine the drug was withdrawn. In 92 of the patients a supine or standing blood pressure of 100 mm. Hg or less was achieved. Eighty of the patients had previously been treated with other potent drugs, and close comparisons and prolonged follow-up in 17 patients showed that diastolic pressures of 100 mm. Hg or less were achieved in more patients after propranolol than with guanethidine, bethanidine, or methyldopa.Sensitivity to propranolol varies widely, and dosage should be increased gradually. The hypotensive effect often takes six to eight weeks to reach its maximum. Propranolol reduces cardiac output but may also act by reducing the cardiac component of pressor stimuli; as a result the baroreceptors gradually regulate the blood pressure at a lower level. It is contraindicated in patients with obstructive airways disease or in uncompensated heart failure.     

Gait stride-to-stride variability and foot clearance pattern analysis in Idiopathic Parkinson’s Disease and Vascular Parkinsonism

The literature on gait analysis in Vascular Parkinsonism (VaP), addressing issues such as variability, foot clearance patterns, and the effect of levodopa, is scarce. This study investigates whether spatiotemporal, foot clearance and stride-to-stride variability analysis can discriminate VaP, and responsiveness to levodopa.Fifteen healthy subjects, 15 Idiopathic Parkinson's Disease (IPD) patients and 15 VaP patients, were assessed in two phases: before (Off-state), and one hour after (On-state) the acute administration of a suprathreshold (1.5 times the usual) levodopa dose. Participants were asked to walk a 30-meter continuous course at a self-selected walking speed while wearing foot-worn inertial sensors. For each gait variable, mean, coefficient of variation (CV), and standard deviations SD1 and SD2 obtained by Poincaré analysis were calculated. General linear models (GLMs) were used to identify group differences. Patients were subject to neuropsychological evaluation (MoCA test) and Brain MRI.VaP patients presented lower mean stride velocity, stride length, lift-off and strike angle, and height of maximum toe (later swing) (p < .05), and higher %gait cycle in double support, with only the latter unresponsive to levodopa. VaP patients also presented higher CV, significantly reduced after levodopa. Yet, all VaP versus IPD differences lost significance when accounting for mean stride length as a covariate.In conclusion, VaP patients presented a unique gait with reduced degrees of foot clearance, probably correlated to vascular lesioning in dopaminergic/non-dopaminergic cortical and subcortical non-dopaminergic networks, still amenable to benefit from levodopa. The dependency of gait and foot clearance and variability deficits from stride length deserves future clarification.     

Levodopa combined with peripheral decarboxylase inhibition in Parkinson's disease

The authors report their experience, over a 26-month period, in the management of 60 parkinsonian patients with the combination of levodopa and an inhibitor of peripheral dopa-decarboxylase, Ro 4-4602. This approach to Parkinson''s disease is useful, safe, and at least as effective as levodopa alone. To date there have been no recognizable toxic effects attributable to Ro 4-4602. This agent appears to prolong the duration of action of levodopa, smoothing out its therapeutic effects. The percentage of patients obtaining a very good and excellent response is slightly increased. There is a possible diminution in the late-occurring bradykinetic and hypotonic freezing episodes. Nausea and cardiac arrhythmias are lessened, as are the incidence and severity of hypotension. Abnormal involuntary movements remain the limiting adverse side effect.