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PubMed1994

Promethazine inhibits osteoclastic bone resorption in vitro.

Several studies have shown that promethazine can reduce age-related osteopenia in mice. Furthermore, prolonged treatment with promethazine (50 mg/day) increases bone mineral content in the lumbar spine in post-menopausal women with osteopenia. However, the mechanism of action of promethazine has not been elucidated. The present study shows that promethazine HCl (0.01-10 microM) dose-dependently inhibits bone resorption by isolated rat osteoclasts in the bone slice assay with an IC50 of approximately 1 microM. Since these concentrations are likely to be achieved in vivo, it is suggested that the beneficial effect of promethazine on osteopenia is at least partly due to a direct inhibitory effect on osteoclast activity.

Aging↗
PubMed1999

Effects of promethazine on bone mass and on bone remodeling in ovariectomized rats: A morphometric, densitometric, and histomorphometric experimental study.

The effect of promethazine on bone is debated. We studied the effect of promethazine on bone and the mechanism of action involved by densitometric and histomorphometric measurements in female Wistar rats (100 days old, mean weight 25 +/- 20 g). A control group of 15 rats was not manipulated. An experimental group of 15 rats were ovariectomized (OVX) at 100 days of life and fed a diet supplemented with 4.8 mg/kg promethazine hydrochloride (OVX + Prom). The group that underwent OVX and a group of 15 rats that underwent sham ovariectomy (Sham-OVX) were not treated with promethazine. After 30 days, all the rats were killed. Their femur and 5th lumbar vertebra were dissected and cleaned of soft tissue. Femoral length and vertebral height were measured with a caliper and bones were weighed on a precision balance. The bone mineral content (BMC) and bone mineral density (BMD) of the whole right femurs and 5th lumbar vertebras were measured by dual-energy X-ray absorptiometry (DXA). Trabecular bone volume (Cn-BV-TV%), trabecular number (Tb-N mm(-1)), trabecular thickness (Tb-Th microm), and trabecular separation (Tb-Sp microm) were measured in the femurs by histomorphometric study of nondecalcified bone. Our results showed that promethazine significantly inhibited postovariectomy loss of bone mass (P < 0. 0001) by significantly reducing bone resorption, as shown by the smaller trabecular spaces observed in the treated OVX rats (P < 0. 0001).

Animals↗
PubMed1983

Effects of thiazinamium chloride, promethazine and chlorpromazine on thromboxane B2 synthesis, phagocytosis and respiratory burst by rat alveolar macrophages.

The effects of three phenothiazines, promethazine, thiazinamium chloride and chlorpromazine, on macrophage function were investigated in rat alveolar macrophages. The study focused on thromboxane B2 (TxB2) synthesis, zymosan phagocytosis, and hexosemonophosphate (HMP) shunt activity in these phagocytes. TxB2 synthesis by resting macrophages was inhibited by thiazinamium chloride and promethazine in a dose-dependent manner. However, chlorpromazine was inhibitory only at 10(-3) M. Promethazine treatment of zymosan-activated macrophages led to a concomitant reduction in both phagocytosis and TxB2 synthesis. Thiazinamium chloride inhibited TxB2 synthesis but had no effect on the ingestion of zymosan particles. In contrast, chlorpromazine inhibited phagocytosis but not TxB2 synthesis except at 10(-3) M. The effects of these agents on the formation of TxB2 synthesis from exogenous arachidonic acid were also investigated. Under these conditions where indomethacin, a known cyclooxygenase inhibitor, was inhibitory, promethazine but not thiazinamium chloride inhibited TxB2 synthesis from exogenous arachidonic acid. Treatment of macrophages with promethazine and chlorpromazine but not thiazinamium chloride results in a reduction in the oxidative burst during phagocytosis. The results suggest that the phenothiazines used in this study differ from one another in their actions on macrophage function. Furthermore, the ability of thiazinamium chloride to selectively inhibit arachidonic acid metabolism may contribute to its bronchodilator/antiallergic activity.

Animals↗
PubMed1987

Effects of chronic administration of codeine and promethazine on breathlessness and exercise tolerance in patients with chronic airflow obstruction.

It has been reported that short-term treatment with relatively high doses of opiates or promethazine causes improvements in dyspnoea and exercise tolerance in patients with chronic airflow obstruction (CAO). This study was designed to determine whether initial benefits were sustained during chronic administration of codeine or promethazine and to compare the two drugs in terms of their efficacy and possible mechanisms of action. Eleven patients with stable CAO were entered into a double-blind, randomized cross-over trial in which codeine (30 mg four times daily) or promethazine (25 mg four times daily) were orally administered for 1-month periods. Treatment effects were assessed by spirometry, arterial blood gases, 12-minute walk distance and subjective dyspnoea ratings. A statistically significant increase from the baseline in mean arterial PCO2 at at 24 hours (P less than 0.01) and at 1 month (P less than 0.05) occurred with codeine administration. There was no significant change from baseline for any other measurement with either drug, and no differences were detected between the two treatment arms. Four of the eleven patients did not complete the study; three of the four experienced worsening of their CAO requiring hospitalization (two while receiving codeine, one while receiving promethazine). We conclude that chronic treatment with either codeine or promethazine provides uncertain benefits to patients with CAO which may not outweigh potential risks.

Aged↗
PubMed1984

Maternal blood pressure response to the intravenous administration of pethidine-promethazine during labor.

A double blind study on the effect of an intravenous injection of a combination of 75 mg pethidine and 25 mg promethazine was conducted on 200 women during normal deliveries. Four groups of 50 women each received injections of pethidine and promethazine, promethazine alone, pethidine alone and normal saline. In the pethidine-promethazine group there was a significant elevation in blood pressure in the first 10 min following the injection as compared with the other groups. The mean (+/- S.D.) systolic blood pressure after the injection was 143.2 +/- 14.3 mmHg as compared with 118.9 +/- 8.4 mmHg before the injection, and the mean diastolic blood pressure as 96.9 +/- 8.4 mmHg after the injection as compared with 77.7 +/- 9.3 mmHg before the injection. 25 mg promethazine alone caused slight elevation in blood pressure which was further increased by combination with pethidine. The clinical significance of these observations is discussed.

Blood Pressure↗
PubMed1986

Effect of promethazine on double tetracycline bone labeling in old mice.

Twenty-five-month-old female B6AF1 mice were injected intramuscularly (i.m.) with declomycin (75 mg/kg) 50 days and 2 days, or 20 days and 2 days, before sacrifice, and cross-sections of their femoral shafts were examined quantitatively for areas of tetracycline fluorescence. Two groups of mice received promethazine HCl in their drinking water (12 mg/dl) for 1 year, and the control groups were untreated. It was found that: the number of discrete areas of cortical and endosteal tetracycline deposition was increased slightly in the groups given promethazine; the length of the endosteal and cortical tetracycline deposits were 2-3 times greater, respectively, in the promethazine treated groups; and the distance between the cortical tetracycline deposits and the endosteum was 2.5 times greater in the promethazine groups. These results support the view that net bone deposition in osteopenic old mice is enhanced by promethazine.

Aging↗
PubMed2003

Antiplasmid effect of promethazine in mixed bacterial cultures.

Promethazine has been recognised as an effective antiplasmid agent in cultures containing a single bacterial species such as Escherichia coli, Yersinia enterocolitica, Staphylococcus aureus and Agrobacterium tumefaciens. The objective of this study was to examine the effect of heterogenity of the microbial flora on plasmid elimination by promethazine in a laboratory based model system of mixed bacterial infection. F'lac plasmid elimination of E. coli K12 LE140 was studied in the presence of a numerically predominant Gram-positive species (Bacillus cereus, Staphylococcus epidermidis) by promethazine (0-120 mg/l) at 23, 37 and 39 degrees C. Growth kinetics of different bacterial species were studied at various temperatures without drug treatment in mixed bacterial cultures and it was found that the small number of added bacteria overgrew the pre-existing flora during the incubation period. We observed that bacterial-bacterial interactions modified the growth rate of individual bacterial species and gave selective advantages to some bacterial species of the microbial community. Some interactions between coexisting bacterial species enhanced the frequency of plasmid curing by promethazine in mixed cultures with S. epidermidis. In our experiments the plasmid curing action of promethazine was more effective at elevated temperature than at lower temperatures.

Anti-Bacterial Agents↗
PubMed1999

Ondansetron/promethazine combination or promethazine alone reduces nausea and vomiting after middle ear surgery.

STUDY OBJECTIVES: To determine the incidence of postoperative nausea and vomiting when a combination of ondansetron and promethazine is given prophylactically, and to ascertain the effect of postoperative nausea and vomiting on recovery room duration and patient satisfaction. DESIGN: Prospective, randomized, placebo-controlled, double-blind study. SETTING: University-affiliated tertiary-care hospital. PATIENTS: 87 ASA physical status I and II adult patients scheduled for middle ear surgery. INTERVENTIONS: Patients were randomly assigned to receive one of the following interventions intravenously: ondansetron 4 mg (Group 1), promethazine 25 mg (Group 2), ondansetron 2 mg plus promethazine 12.5 mg (Group 3, combination), or placebo (Group 4). MEASUREMENTS AND MAIN RESULTS: Independent, study blinded observers recorded complaints of nausea and number of episodes of vomiting for 24 hours following the patient's first response to commands. All patients were contacted the day after discharge to inquire about nausea and vomiting. The awakening time, postanesthesia care unit and day surgery unit durations, opioid use, and side effects were recorded. At the end of the 24-hour period, the study blinded observers asked patients for an overall assessment of their global anesthesia experience using an 11-point scale. During the 24-hour period, the incidence of postoperative nausea and vomiting was reduced from 74% (placebo) to 39% (promethazine; p = 0.03) and 29% (combination; p = 0.003). Compared with placebo, the severity of vomiting was significantly less in the combination group (p = 0.04). The number of very satisfied patients correlated negatively with the incidence of postoperative nausea and vomiting (p < 0.0001) and with the severity of vomiting (p = 0.003). CONCLUSION: The prophylactic use of an antiemetic with middle ear surgery may reduce postoperative nausea and vomiting over 24 hours, and the ondansetron/promethazine combination or promethazine alone are cost-effective choices. Finally, the combination reduced significantly the severity of vomiting.

Adolescent↗
PubMed1981

Methods to assess breathlessness in healthy subjects: a critical evaluation and application to analyse the acute effects of diazepam and promethazine on breathlessness induced by exercise or by exposure to raised levels of carbon dioxide.

1. Methods were devised and evaluated for inducing breathlessness by submaximal graded exercise in healthy subjects while objective measurements of cardiorespiratory function were made. Breathlessness was assessed with serial visual analogue scales (VAS), but with various measures to enhance repeatability. 2. A high level of reproducibility was obtained in spite of the subjective nature of the assessment. Individual responses were described by the relationship between breathlessness and ventilation. The sensitivity of the method was demonstrated by the use of inspiratory resistances which disturbed this relationship and caused greater breathlessness for a given level of ventilation. 3. These methods were applied to six healthy subjects to analyse the effects of acute doses of diazepam and promethazine on breathlessness induced by graded exercise or by rebreathing carbon dioxide in a double-blind study. 4. During exercise, diazepam and promethazine did not reduce breathlessness, although there was a minor trend with promethazine. During exposure to elevated levels of carbon dioxide, diazepam and promethazine had no effect on breathlessness. Diazepam and promethazine produced similar levels of sedation, but neither drug had significant effects on the ventilatory response to carbon dioxide. These preliminary findings contrast with those reported for chronic diazepam in 'pink puffers'. 5. Raised levels of carbon dioxide caused greater breathlessness in relation to ventilation than did exercise.

Adult↗
PubMed2000

Pharmacokinetics of promethazine hydrochloride after administration of rectal suppositories and oral syrup to healthy subjects.

The pharmacokinetics of promethazine hydrochloride after administration of rectal suppositories at three dosage strengths and oral syrup were studied. The study had an open-label, randomized, crossover design. At intervals of five to nine days, healthy volunteers were given two 12.5-mg promethazine rectal suppositories, one 25-mg suppository, one 50-mg suppository, or 50 mg (10 mL) of promethazine oral syrup. Blood samples were collected before each dose and at intervals from 0.5 to 48 hours afterward. Promethazine concentration was determined by high-performance liquid chromatography, and pharmacokinetic values were calculated with noncompartmental methods. Thirty-six subjects (18 men and 18 women) completed the study. Absorption was highly variable for all the formulations. On average, absorption was more rapid and the maximum plasma concentration (Cmax) higher for the syrup than for the suppositories. Cmax was significantly lower for the 50-mg suppository (mean, 9.04 ng/mL) than for the syrup (19.3 ng/mL). The time to Cmax (tmax) was significantly shorter for the syrup (mean, 4.4 hours) than for the suppositories (6.7-8.6 hours). There were no significant differences in dose-normalized Cmax among the three suppository treatments. Area under the concentration-versus-time curve (AUC) was comparable between the syrup and the 50-mg suppository and between the treatments with two 12.5-mg suppositories and the 25-mg suppository. Elimination profiles were similar among all treatments (mean half-life [t1/2], 16-19 hours). There were no significant differences in pharmacokinetics on the basis of sex or race. The mean relative bioavailability for the three suppository treatments ranged from 70% to 97%. Individual relative bioavailabilities ranged from 4% to 343%. The pharmacokinetics of promethazine administered in oral syrup and rectal suppositories were highly variable, but, in general, the suppositories produced a lower Cmax and later tmax than the syrup. All formulations were comparable in terms of dose-normalized AUC and t1/2, and the three suppository treatments were comparable in terms of dose-normalized Cmax.

Administration, Oral↗
PubMed2003

Histamine H1-receptor antagonists, promethazine and homochlorcyclizine, increase the steady-state plasma concentrations of haloperidol and reduced haloperidol.

The effects of histamine H1-receptor antagonists, promethazine and homochlorcyclizine, both of which are inhibitors of CYP2D6, on the steady-state plasma concentrations (Css) of haloperidol and reduced haloperidol were studied in 23 schizophrenic inpatients receiving haloperidol, 12 to 36 mg/d, for 2 to 29 weeks. Promethazine, 150 mg/d, in 11 patients and homochlorcyclizine, 60 mg/d, in the others were coadministered for at least 1 week. Blood sampling was performed before and during coadministration of promethazine or homochlorcyclizine and 1 week after the discontinuation, together with clinical assessments by Brief Psychiatric Rating Scale (BPRS) and Udvalg for kliniske undersogelser (UKU) side effect rating scale. The Css (mean +/- SD) of haloperidol and reduced haloperidol during promethazine coadministration (27.6 +/- 24.9 and 8.6 +/- 13.2 ng/mL) were significantly higher than those before the coadministration (12.7 +/- 10.8 and 5.0 +/- 6.0 ng/mL; P < 0.01) or 1 week after the discontinuation (15.6 +/- 14.8 and 5.8 +/- 7.9 ng/mL; P < 0.05). The Css of haloperidol and reduced haloperidol during homochlorcyclizine coadministration (14.9 +/- 8.1 and 6.4 +/- 5.4 ng/mL) were also significantly higher than those before the coadministration (10.9 +/- 7.2 and 3.8 +/- 3.6 ng/mL; P < 0.01) or 1 week after the discontinuation (12.9 +/- 7.4 and 4.8 +/- 4.1 ng/mL; P < 0.05). No change in BPRS or UKU score was found throughout the study. Thus, the current study suggests that coadministration of clinical doses of promethazine and homochlorcyclizine increases the Css of haloperidol and reduced haloperidol via the inhibitory effects on the CYP2D6-catalyzed metabolism of haloperidol and reduced haloperidol.

Adult↗
PubMed1999

Sequential randomised and double blind trial of promethazine prophylaxis against early anaphylactic reactions to antivenom for bothrops snake bites.

OBJECTIVE: To investigate the efficacy of the H1 antihistamine promethazine against early anaphylactic reactions to antivenom. DESIGN: Sequential randomised, double blind, placebo controlled trial. SETTING: Public hospital in a venom research institute, São Paulo, Brazil. PARTICIPANTS: 101 patients requiring antivenom treatment after being bitten by bothrops snakes. INTERVENTION: Intramuscular injection of promethazine (25 mg for adults and 0.5/kg for children) or placebo given 15-20 min before starting intravenous infusion of antivenom. MAIN OUTCOME MEASURES: Incidence and severity of anaphylactic reactions occurring within 24 hours after antivenom. RESULTS: Reactions occurred in 12 of 49 patients treated with promethazine (24%) and in 13 of 52 given placebo (25%); most were mild or moderate. Continuous sequential analysis indicated that the study could be interrupted at the 22nd untied pair, without preference for promethazine or placebo. CONCLUSION: Prophylaxis with promethazine does not prevent early reactions. Patients should be observed carefully during antivenom infusion and the subsequent few hours.

Adolescent↗
PubMed2003

Rapid tranquillisation for agitated patients in emergency psychiatric rooms: a randomised trial of midazolam versus haloperidol plus promethazine.

OBJECTIVE: To compare two widely used drug treatments for people with aggression or agitation due to mental illness. DESIGN: Pragmatic, randomised clinical trial. SETTING: Three psychiatric emergency rooms in Rio de Janeiro, Brazil. SUBJECTS: 301 aggressive or agitated people. INTERVENTIONS: Open treatment with intramuscular midazolam or intramuscular haloperidol plus promethazine. MAIN OUTCOME MEASURES: Patients tranquil or sedated at 20 minutes. SECONDARY OUTCOMES: patients tranquil or asleep by 40, 60, and 120 minutes; restrained or given extra drugs within 2 hours; severe adverse events; another episode of agitation or aggression; needing extra visits from doctor during first 24 hours; overall antipsychotic load in first 24 hours; and not discharged by two weeks. RESULTS: 151 patients were randomised to midazolam, and 150 to haloperidol-promethazine mix. Follow up for the primary outcome was available for 298 (99%): 134/151 (89%) of patients given midazolam were tranquil or asleep after 20 minutes compared with 101/150 (67%) of those given haloperidol plus promethazine (relative risk 1.32 (95% confidence interval 1.16 to 1.49)). By 40 minutes, midazolam still had a statistically and clinically significant 13% relative advantage (1.13 (1.01 to 1.26)). After 1 hour, about 90% of both groups were tranquil or asleep. One important adverse event occurred in each group: a patient given midazolam had transient respiratory depression, and one given haloperidol-promethazine had a grande mal seizure. CONCLUSIONS: Both treatments were effective. Midazolam was more rapidly sedating than haloperidol-promethazine, reducing the time people are exposed to aggression. Adverse effects and resources to deal with them should be considered in the choice of the treatment.

Adult↗
PubMedDate not supplied

Promethazine treatment of steroid-induced psychosis in a child.

OBJECTIVE: To report a case of steroid-induced psychosis in a child that resolved with the treatment of promethazine, a phenothiazine derivative. CASE SUMMARY: A 2-year-old white boy with a history of relapsed acute lymphoblastic leukemia underwent a bone marrow transplant and developed graft-versus-host disease, which was treated with methylprednisolone. Within 24 hours of initiation of the methylprednisolone, the patient developed symptoms associated with steroid-induced psychosis including mania, head-banging, and excessive crying. Because the corticosteroid could not be discontinued, promethazine, a phenothiazine derivative, was used to treat the psychotic symptoms. Symptoms resolved with use of promethazine. DISCUSSION: A number of published reports describe the appearance of psychological symptoms with corticosteroid use. While the mechanism is unclear, the reaction is usually reversible with dose reduction or discontinuation of the corticosteroid. In cases where this cannot be done, typical treatment involves an antipsychotic medication. Most antipsychotic medications, such as the phenothiazine class, have not been evaluated in very young children. Promethazine is a phenothiazine derivative that has been used in children for a number of nonpsychiatric indications. CONCLUSIONS: Promethazine may be effective in treating steroid-induced psychosis in pediatric patients.

Anti-Inflammatory Agents↗
PubMedDate not supplied

Comparison of ketorolac-chlorpromazine with meperidine-promethazine for treatment of exacerbations of chronic pain.

BACKGROUND: The aim was to compare the efficacy and safety of a combination of intramuscular ketorolac and chlorpromazine for the treatment of acute exacerbations of chronic pain with the more commonly used regimen of intramuscular meperidine and promethazine. METHODS: Use-effective case series were drawn from a real-life, rural emergency department practice, in which 200 consecutive patients coming to a rural emergency department with acute exacerbations of chronic pain syndromes were assigned on an every-other basis in a single-blind fashion to one of the two treatment conditions. Patients were given intramuscular doses of either 60 mg of ketorolac plus 50 mg of chlorpromazine (75 mg of chlorpromazine for patients weighing more than 100 kg), or 50 mg of meperidine plus 25 mg of promethazine (50 mg of promethazine for patients weighing more than 75 kg); patients weighing more than 100 kg were given 1.5 doses. Patients older than 65 years or whose blood pressure at the time of injection was less than 110/70 mmHg were given half-doses. Patients could receive one additional half-dose injection if they had no results within 30 to 60 minutes after the first injection. Patients were assessed on self-report and on a verbal and visual analog scale of pain rating. Temperature, blood pressure, heart rate, and respirations were monitored every 15 minutes. RESULTS: Both regimens performed well, with more than 90 percent of patients reporting good or excellent improvement on acute exacerbations of chronic pain. Ketorolac-chlorpromazine offered significant advantages compared with meperidine-promethazine when patients rated their pain on a visual analog pain scale (P < 0.05) but not on a verbal scale. Adverse reactions were minimal and consisted of more respiratory tract depression with meperidine and more vertigo or dizziness with chlorpromazine. There was no difference in incidence of hypotension between the two groups. CONCLUSIONS: The combination of ketorolac and chlorpromazine is a safe and efficacious alternative to meperidine plus promethazine for the treatment of exacerbations of chronic pain in the rural emergency department setting.

Adolescent↗
PubMed2000

Promethazine affects optokinetic but not vestibular responses in monkeys.

BACKGROUND: Promethazine is used to treat motion sickness including Space Adaptation Syndrome, but there is incomplete information about how it affects vestibular and optokinetic responses. METHODS: Vestibular and optokinetic nystagmus, recorded with eye coils, were characterized in monkeys after administration of promethazine at dosages approximately equivalent to those used by humans in space. RESULTS: The initial increase of horizontal eye velocity during optokinetic nystagmus (OKN) was reduced after receiving the drug. Consequently, it took a longer time for eye velocity to rise to 60% of steady state value, the normal initial jump in eye velocity. Steady state OKN, maximum gains of optokinetic after-nystagmus (OKAN) and OKAN falling time constants were unaffected. The gains and time constants of the horizontal, vertical and roll angular vestibulo-ocular reflex (aVOR), the amplitude and velocity of saccades, and ocular counter-rolling (OCR), induced by off-vertical axis rotation (OVAR) were unaffected by promethazine. A two-component optokinetic model simulated the data simply by reducing the gain of the initial (rapid) component of OKN. A reduction in coupling between a non-linear element and the velocity storage integrator was required to simulate some vertical OKN data. CONCLUSIONS: Promethazine reduces the gain of the direct visual-oculomotor pathway in monkeys. It has little effect on saccades, the gain and time constant of the aVOR and the low frequency linear vestibulo-ocular reflex (IVOR), which orients the eyes during ocular counterrolling. The optokinetic deficit is consistent with reported reduction in ocular pursuit and VOR suppression after promethazine in humans.

Animals↗
PubMed1982

Promethazine hydrochloride therapy in severely Rh-sensitized pregnancies.

Seventeen severely Rh-sensitized women were treated with promethazine hydrochloride (Phenergan) in 18 pregnancies, according to a protocol described by Gusdon et al. There was an unequivocal amelioration of the disease process in 10 of the pregnancies. In 9 of these 10 pregnancies, the infant survived. In 4 of the pregnancies, promethazine proved an unnecessary therapy as the infants were Rh negative. Promethazine may or may not have been helpful in 2 pregnancies, both of which resulted in live-born infants. One pregnancy resulted in intrauterine fetal death subsequent to an intrauterine transfusion. This infant was later shown to have multiple congenital anomalies incompatible with life. In a subsequent pregnancy, the mother was again treated with promethazine and had a normal infant who survived after exchange transfusions. The one loss of a live-born infant resulted from a cardiac arrest during an exchange transfusion. On the basis of these observations, the authors agree with Gusdon et al that promethazine does have an ameliorating effect on Rh-sensitized pregnancies.

Abnormalities, Drug-Induced↗
PubMed1994

Competition between dopamine, beta-receptor agonists and promethazine in Escherichia coli plasmid replication.

The substrates in the phenylalanine, metabolism play key roles in the physiological processes of bacteria. Promethazine affects the phenylalanine metabolism in Escherichia coli. The antibacterial and anti-plasmid actions of promethazine were prevented by phenylalanine, tyrosine, phenylpyruvic acid, phenylacetic acid, noradrenaline and dopamine in minimal medium. Isoproterenol (and phenoxybenzamine) reduced, while propranolol, oxyprenolol and alprenolol isomers enhanced the anti-plasmid effect of promethazine. Propranolol itself induced an anti-plasmid effect. The effects of beta-receptor agonists and antagonists on promethazine-induced anti-plasmid action serve as an indirect evidence of beta adrenergic like binding sites in E. coli. These binding sites are involved in the plasmid replication process and are connected with promethazine binding sites in bacteria.

Adrenergic beta-Agonists↗