Antisialogogue drugs in man; comparison of atropine, scopolamine (1-hyoscine) and 1-hyoscyamine (bellafoline)

Understanding Central Nervous System Effects of Deliriant Hallucinogenic Drugs through Experimental Animal Models

Hallucinogenic drugs potently alter human behavior and have a millennia-long history of use for medicinal and religious purposes. Interest is rapidly growing in their potential as CNS modulators and therapeutic agents for brain conditions. Antimuscarinic cholinergic drugs, such as atropine and scopolamine, induce characteristic hyperactivity and dream-like hallucinations and form a separate group of hallucinogens known as "deliriants". Although atropine and scopolamine are relatively well-studied drugs in cholinergic physiology, deliriants represent the least-studied class of hallucinogens in terms of their behavioral and neurological phenotypes. As such, novel approaches and new model organisms are needed to investigate the CNS effects of these compounds. Here, we comprehensively evaluate the preclinical effects of deliriant hallucinogens in various animal models, their mechanisms of action, and potential interplay with other signaling pathways. We also parallel experimental and clinical findings on deliriant agents and outline future directions of translational research in this field.

Comparison of the Effects of Atropine and Glycopyrrolate on various End-Organs1

Atropine and glycopyrrolate (glycopyrronium bromide), a quaternary ammonium drug, were evaluated in volunteers following intramuscular administration with respect to effects on various end-organs with cholinergic innervation. Glycopyrrolate appears to be five to six times more potent than atropine in its antisialogogue effect and also exhibits a selective, though prolonged, effect on salivary secretion and sweat gland activity. It has minimal cardiovascular, ocular and central nervous system effects.

Sublingual atropine drops for the treatment of pediatric sialorrhea

Excess oral secretions or sialorrhea is a common problem affecting children and adults with neurological disorders, as well as those approaching the end of life because of a variety of underlying illnesses. Systemic anticholinergic medications are often prescribed in an attempt to improve quality of life and reduce complications; yet, response rates are variable, and a sizable proportion of patients discontinue these drugs as a result of intolerable side effects. This report describes the successful use of a local treatment, sublingually delivered ophthalmic atropine drops, to reduce sialorrhea in a child receiving palliative care. In addition, medical evidence for the safety and efficacy of traditionally prescribed systemic medications for the treatment of pediatric sialorrhea is reviewed.

Anticholinergics improve fibreoptic intubating conditions during general anaesthesia

PURPOSE

To determine if anticholinergic agents improve fibreoptic intubating conditions and to compare the efficacy and side effects of glycopyrrolate and hyoscine.

METHODS

Eighty ASA I adults undergoing elective wisdom tooth extraction were randomly allocated to receive 0.4 mg hyoscine hydrobromide po, 0.4 mg hyoscine hydrobromide im, 0.4 mg glycopyrrolate im or no anticholinergic, one hour pre-operatively. All underwent nasal fibreoptic intubation under general anaesthesia. The time taken to pass the fibreoptic scope was noted and visual analogue scores (VAS) were recorded for clarity of visual field and post-operative sore throat, dry mouth and nausea.

RESULTS

The time to intubation was not different among the four groups (Kruschal-Wallis P = 0.07). The clarity of visual field was improved in all three anticholinergic groups (Kruschal-Wallis P = 0.006), but there was no difference among the three groups (median VAS control 6.4, glycopyrrolate 8.0, oral hyoscine 7.9, im hyoscine 7.7). There was no difference in post-operative side effects among any of the groups at both 30 min and four hours.

CONCLUSION

The addition of an anticholinergic produced better visual conditions for intubation but had no effect on the incidence of post-operative sore throat, dry mouth and nausea.

Nonsurgical treatment of drooling in a patient with closed head injury and severe dysarthria

The purpose of this investigation was to measure the effectiveness of the antimuscarinic drug atropine sulfate in the treatment of chronic drooling in a patient with a history of severe closed head injury and resultant widespread oral neuromuscular and higher cortical disturbances. Results of the A-B-A-B-A-B withdrawal paradigm, chosen to demonstrate the functional relationship between drug therapy and the degree of drooling, revealed that administration of atropine sulfate reduced by more than 50% of baseline levels the amount of resting secretion, intraoral accumulation, and pharyngeal-laryngeal pooling of saliva, with negligible side effects. These results are discussed and compared to the alternative drug and surgical approaches to treatment that have been the primary focus of recent research on drooling.

Plasma lignocaine levels during paediatric endoscopy of the upper respiratory tract. Relationship with mucosal moistness

Plasma lignocaine levels were measured at 5, 10 and 15 minutes following local application (4 mg/kg) to the upper airway in children who underwent endoscopy under general anaesthesia. These levels were then correlated with the appearance of the moistness of the airway mucosa secondary to premedication with atropine. This latter assessment was carried out by one anaesthetist who used a predetermined scale of 1-5, where 1 was very dry and 5 very wet. Significantly higher (p less than 0.05) plasma levels of lignocaine were achieved when the mucosa was 'very dry' especially in children under 2 years of age. The total dose of lignocaine applied to the upper airway of children should probably be reduced, in the presence of a 'dry' mucosa after effective antisialogogue premedication, and especially when less than 2 years of age.

Atropine and hyoscine

The drugs atropine and hyoscine are reviewed in the context of their use by anaesthetists. The results of recent studies are stressed and guidelines given for use of these drugs in modern anaesthetic practice.

Evaluation of the anticholinergic actions of glycopyrronium bromide

1. Glycopyrronium was evaluated by intramuscular, intravenous and oral routes in six adult volunteers for its efficacy as an antisialogogue as also for its action on other aspects of cholinergic activity. 2. It was found to be an effective antisialogogue of long duration of action by all three routes. When given orally the effects were delayed in onset and persisted for too long. Intramuscular and intravenous routes were useful. The intramuscular absorption of the drug is rapid and consistent. 3. Sweat gland activity was affected in a similar fashion but less consistently and other parameters were mostly unaffected. 4. Glycopyrronium 0.2 mg intramuscularly was found to be the optimal dose. Larger doses produced subjective discomfort out of proportion to a further reduction in salivary secretion. 5. Intravenous administration causes no changes in cardiovascular stability.

Glycopyrrolate methobromide: 2. comparison with atropine sulphate in anaesthesia

A double blind study of 98 patients was undertaken to compare the clinical usefulness of atropine and glycopyrrolate for pre-anaesthetic medication and their relative effectiveness in antagonizing the muscarinic effects of neostigmine methylsulphate given to reverse neuromuscular blockade. Intramuscular administration of atropine 0.4 mg or of glycopyrrolate 0.2 mg produced the same degree of dryness of the pharynx. However, glycopyrrolate was found to be a more potent antagonizer of the increased salivation induced by neostigmine. By intramuscular administration, both drugs produced the same degree of tachycardia, although atropine tended to cause no change in the pulse rate or even to produce bradycardia in a greater number of patients. Administered intravenously, atropine produced a more significant tachycardia in a large number of patients prior to neostigmine administration, although the protection against a decreased pulse rate from neostigmine is greater in those patients who received glycopyrrolate. It would appear, therefore, that glycopyrrolate is more effective in antagonizing the muscarinic effects of neostigmine methylsulphate.