Pharmacokinetics of intravenous procaine infusion in humans

The Local Anaesthetic Procaine Prodrugs ProcCluster® and Procaine Hydrochloride Impair SARS-CoV-2 Replication and Egress In Vitro

As vaccination efforts against SARS-CoV-2 progress in many countries, there is still an urgent need for efficient antiviral treatment strategies for those with severer disease courses, and lately, considerable efforts have been undertaken to repurpose existing drugs as antivirals. The local anaesthetic procaine has been investigated for antiviral properties against several viruses over the past decades. Here, we present data on the inhibitory effect of the procaine prodrugs ProcCluster® and procaine hydrochloride on SARS-CoV-2 infection in vitro. Both procaine prodrugs limit SARS-CoV-2 progeny virus titres as well as reduce interferon and cytokine responses in a proportional manner to the virus load. The addition of procaine during the early stages of the SARS-CoV-2 replication cycle in a cell culture first limits the production of subgenomic RNA transcripts, and later affects the replication of the viral genomic RNA. Interestingly, procaine additionally exerts a prominent effect on SARS-CoV-2 progeny virus release when added late during the replication cycle, when viral RNA production and protein production are already largely completed.

High-precision monitoring of and feedback control over drug concentrations in the brains of freely moving rats

Knowledge of drug concentrations in the brains of behaving subjects remains constrained on a number of dimensions, including poor temporal resolution and lack of real-time data. Here, however, we demonstrate the ability of electrochemical aptamer-based sensors to support seconds-resolved, real-time measurements of drug concentrations in the brains of freely moving rats. Specifically, using such sensors, we achieve <4 μM limits of detection and 10-s resolution in the measurement of procaine in the brains of freely moving rats, permitting the determination of the pharmacokinetics and concentration-behavior relations of the drug with high precision for individual subjects. In parallel, we have used closed-loop feedback-controlled drug delivery to hold intracranial procaine levels constant (±10%) for >1.5 hours. These results demonstrate the utility of such sensors in (i) the determination of the site-specific, seconds-resolved neuropharmacokinetics, (ii) enabling the study of individual subject neuropharmacokinetics and concentration-response relations, and (iii) performing high-precision control over intracranial drug levels.

Procaine-The Controversial Geroprotector Candidate: New Insights Regarding Its Molecular and Cellular Effects

Since its discovery in 1905 and its employment in everyday medical practice as a local anesthetic, to its highly controversial endorsement as an "anti-aging" molecule in the sixties and seventies, procaine is part of the history of medicine and gerontoprophylaxis. Procaine can be considered a "veteran" drug due to its long-time use in clinical practice, but is also a molecule which continues to incite interest, revealing new biological and pharmacological effects within novel experimental approaches. Therefore, this review is aimed at exploring and systematizing recent data on the biochemical, cellular, and molecular mechanisms involved in the antioxidant and potential geroprotective effects of procaine, focusing on the following aspects: (1) the research state-of-the-art, through an objective examination of scientific literature within the last 30 years, describing the positive, as well as the negative reports; (2) the experimental data supporting the beneficial effects of procaine in preventing or alleviating age-related pathology; and (3) the multifactorial pathways procaine impacts oxidative stress, inflammation, atherogenesis, cerebral age-related pathology, DNA damage, and methylation. According to reviewed data, procaine displayed antioxidant and cytoprotective actions in experimental models of myocardial ischemia/reperfusion injury, lipoprotein oxidation, endothelial-dependent vasorelaxation, inflammation, sepsis, intoxication, ionizing irradiation, cancer, and neurodegeneration. This analysis painted a complex pharmacological profile of procaine: a molecule that has not yet fully expressed its therapeutic potential in the treatment and prevention of aging-associated diseases. The numerous recent reports found demonstrate the rising interest in researching the multiple actions of procaine regulating key processes involved in cellular senescence. Its beneficial effects on cell/tissue functions and metabolism could designate procaine as a valuable candidate for the well-established Geroprotectors database.

Mechanisms of Action by Which Local Anesthetics Reduce Cancer Recurrence: A Systematic Review

BACKGROUND

Surgery in concert with anesthesia is a key part of the management of advanced-stage cancers. Anesthetic agents such as opioids and volatile anesthetics have been shown to promote recurrence in preclinical models, whereas some animal models have shown that the use of lidocaine may be beneficial in reducing cancer recurrence. The purpose of this article is to review the current literature to highlight the mechanisms of action by which local anesthetics are thought to reduce cancer recurrence.

METHODS

A systematic review was conducted using the PubMed (1966 to 2018) electronic database. Search terms included "lidocaine," "ropivicaine," "procaine," "bupivicaine," "mepivicaine," "metastasis," "cancer recurrence," "angiogenesis," and "local anesthetics" in various combinations. The search yielded 146 total abstracts for initial review, 20 of which met criteria for inclusion. Theories for lidocaine's effect on cancer recurrence were recorded. All studies were reviewed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist.

RESULTS

Numerous mechanisms were proposed based on the local anesthetic used and the type of cancer. Mechanisms include those that are centered on endothelial growth factor receptor, voltage-gated sodium and calcium channels, transient receptor melanoplastin 7, hyperthermia, cell cycle, and demyelination.

CONCLUSIONS

In vivo models suggest that local anesthetic administration leads to reduced cancer recurrence. The etiology of this effect is likely multifactorial through both inhibition of certain pathways and direct induction of apoptosis, a decrease in tumor migration, and an association with cell cycle-mediated and DNA-mediated effects. Additional research is required to further define the clinical implications.

A Clickable Analogue of Ketamine Retains NMDA Receptor Activity, Psychoactivity, and Accumulates in Neurons

Ketamine is a psychotomimetic and antidepressant drug. Although antagonism of cell-surface NMDA receptors (NMDARs) may trigger ketamine’s psychoactive effects, ketamine or its major metabolite norketamine could act intracellularly to produce some behavioral effects. To explore the viability of this latter hypothesis, we examined intracellular accumulation of novel visualizable analogues of ketamine/norketamine. We introduced an alkyne “click” handle into norketamine (alkyne-norketamine, A-NK) at the key nitrogen atom. Ketamine, norketamine, and A-NK, but not A-NK-amide, showed acute and persisting psychoactive effects in mice. This psychoactivity profile paralleled activity of the compounds as NMDAR channel blockers; A-NK-amide was inactive at NMDARs, and norketamine and A-NK were active but ~4-fold less potent than ketamine. We incubated rat hippocampal cells with 10 μM A-NK or A-NK-amide then performed Cu²⁺ catalyzed cycloaddition of azide-Alexa Fluor 488, which covalently attaches the fluorophore to the alkyne moiety in the compounds. Fluorescent imaging revealed intracellular localization of A-NK but weak A-NK-amide labeling. Accumulation was not dependent on membrane potential, NMDAR expression, or NMDAR activity. Overall, the approach revealed a correlation among NMDAR activity, intracellular accumulation/retention, and behavioral effects. Thus, we advance first generation chemical biology tools to aid in the identification of ketamine targets.

[Differentiation of peripheral and central hyperalgesic effects of systemic procaine]

OBJECTIVE

The aim of this study was to differentiate between the peripheral and central analgesic and antihyperalgesic properties of systemic procaine hydrochloride in standardized human pain models.

METHOD

Subcutaneous injections of either 150 mg procaine hydrochloride or saline solution were administered at intervals of 2 weeks on a randomized and double blind basis. During the 90-min infusion and subsequent 60-min monitoring periods, touch sensitivity was determined and in addition two experimental hyperalgesic models were analyzed.

RESULTS

While touch sensitivity was not affected by procaine hydrochloride, development of primary mechanical hyperalgesia was significantly reduced.

CONCLUSION

The concentration of procaine hydrochloride used in our experiment elicited peripheral antihyperalgesic effects without central venous side effects. These results can account for the clinical effect of low-dose procaine hydrochloride in pain conditions exhibiting pronounced hyperalgesia.

Comparison of the reinforcing efficacy of cocaine and procaine in rhesus monkeys responding under a progressive-ratio schedule

Rhesus monkeys (n = 5) were prepared with chronic IV catheters and trained to lever press under a PR schedule of drug injection. The schedule consisted of five components, each made up of four trials (i.e., 20 trials total). Each trial within a component had the same response requirement. The response requirement in the first component was 120/trial and doubled in successive components to a maximum of 1920 in the fifth. A trial ended with an injection or the expiration of a 12-min limited hold (LH). The inter-trial interval (ITI) was 15 or 30 min. Following an injection or expiration of the LH, all stimulus lights were extinguished and responding had no consequence for the remainder of the trial. A session ended when either all 20 injections were self-administered or the response requirement was not met within the LH for two consecutive trials. The number of injections/session and responses/session increased with dose for cocaine (0.012-0.1 mg/kg per injection) and procaine (0.12-2.0 mg/kg per injection) at both ITI values. At the 15-min ITI, responding decreased again at higher doses in some monkeys with cocaine and in all monkeys with procaine. At maximum, cocaine maintained significantly more injections and responses/session when the ITI was 30 min than when it was 15 min. In contrast, the increase in ITI did not increase the maximum maintained by procaine. Cocaine was approximately 10-fold more potent than procaine and maintained at maximum significantly more injections and responses than procaine when ITI was 30 min but not when the ITI was 15 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Intracavernous injection of prostaglandin E1 plus procaine in the treatment of erectile dysfunction

Despite the availability of prostaglandin E1 for more than 7 years as a diagnostic and therapeutic tool in patients with erectile dysfunction, the problem of penile discomfort after prostaglandin E1 application has remained unsolved. In a randomized, double-blind, crossover study we investigated the effect of 2 different prostaglandin E1-procaine concentrations on 24 patients suffering from pain following intracorporeal injection of prostaglandin E1 alone. Intracavernous injection of 20 micrograms. prostaglandin E1 with 10 mg. procaine (study 1) failed to improve local painful sensations. The combination of 20 micrograms. prostaglandin E1 with 20 mg. procaine (study 2) decreased the incidence of local pain significantly (p < 0.01). These preliminary results show that the combination of prostaglandin E1 plus procaine represents a beneficial alternative in patients with penile pain due to the single substance.

Discriminative stimulus properties of cocaine. Effects of apomorphine, haloperidol, procaine and other drugs

In pigeons trained to discriminate between the presence and absence of 3 mg/kg of cocaine, combinations of intramuscularly injected (i.m.) procaine (0.7-7.0 mg/kg) plus cocaine (0.3-3.0 mg/kg) did not alter the drug (cocaine)-dose generalization curve as compared to cocaine alone although tests with large doses of procaine given alone (30.0 and 56.0 mg/kg) engendered dose-related responding appropriate to cocaine. Apomorphine (0.56 mg/kg, i.m.) also elicited more than 50% cocaine-appropriate responding, as did doses of 10 mg/kg of intragastrically administered cocaine, given by gavage at the opening of the proventriculus; of the two treatment-test intervals (15 and 30 min) examined the generalization effect was greater at 30 min as compared to 15 min after administration. D-Lysergic acid diethylamide (0.1 mg/kg) morphine (3.0 mg/kg), pentobarbital (10.0 mg/kg), and delta 9-tetrahydrocannabinol (0.3 mg/kg) caused less than 16% pecking responses on the cocaine-appropriate key. The discriminative stimulus effects of cocaine (3.0 mg/kg) were attenuated in a dose-related manner by the neuroleptic haloperidol (dose range tested: 0.1-1.0 mg/kg). Neither the antagonism, nor the substitution tests with haloperidol were accompanied by a significant change in the percentage of responding on the initially selected position (key) by the pigeons.

Haemodynamic effects of intravenous procaine as a supplement to general anaesthesia in patients with valvular heart disease

The effect of intravenous procaine, 2 mg/kg/min, on the cardiovascular function of nine patients scheduled for cardiac valve replacement was studied under enflurane-pancuronium anaesthesia. Procaine infusion was started after intubation during steady-state anaesthesia, and continued until start of cardiopulmonary by-pass. Systemic vascular resistance decreased steadily from 198.2 +/- 28.7 to 133.0 +/- 17.2 kPa X s/l (P less than 0.05). A simultaneous decline in mean arterial pressure from 10.13 +/- 0.68 to 7.47 +/- 0.48 kPa was observed (P less than 0.01). Cardiac index, heart rate, central venous pressure, pulmonary arterial mean pressure and pulmonary capillary wedge pressure were all unaffected by procaine as well as by surgical stimulation. It is concluded that continuous procaine infusion as an adjuvant to general anaesthesia effectively abolishes the hypertensive and tachycardiac response to surgical stimulation. The limiting factor in the amount of infused procaine appears to be the hypotension caused by vasodilation, not myocardial depression or convulsions.

Reappraisal of intravenous procaine as a short-acting anesthetic adjuvant

Our data in 74 patients demonstrate that procaine hydrochloride is a safe anesthetic adjuvant in doses of 1 mg/kg/min even when total doses are 5 to 7 g. Blood pressure, heart rate, electrocardiographic variables, and blood gases were not adversely affected. Patients had no nausea or untoward postanesthesia symptoms. Emergence from anesthesia was rapid, within less than 15 minutes in all patients, and most were fully awake before leaving the operating room. In two patients in whom blood levels were studied the drug disappeared within 40 minutes. Procaine is inexpensive, $1.16 for 10 g, and it is not a known liver or kidney toxin. Until studies on cardiovascular dynamics and analgesic effects as in whom a low plasma cholinesterase activity is present or suspected. The clinical appraisal in 56 patients indicates its usefulness in suppressing premature venticular contractions and cough reflexes during endoscopic procedures in the respiratory tract. Procaine can be used to advantage in supplementing general anesthesia in outpatient surgery because of its brief action. For these reasons, the drug merits further study.