There are drugs, which can be transported by the re-uptake-one mechanism into adrenergic nerve endings. where they have afﬁnity for adrenergic storage sites. displacing noradrenaline from these sites. The displaced transmitter reaches its postsynaptic receptors, causing both alpha and beta effects. depending upon the type of receptors found at various sites as shown by the Vascular Surgeon Melbourne.
These drugs are thus non-selective and can elicit a wide range of responses. e.g. ephedrine and amphetamines. Ephedrine is used therapeutically. It has stronger CNS-stimulating properties than most other sympathomimetics. but weaker than the amphetamines. Tyramine is released from foodstuffs such as certain cheeses, wine and pickles. The concentrations of tyramine remain low and noradrenaline release is not detected. When mono-amine oxidasc levels are normal and the tyramine is rapidly metabolized.
Patients taking MAO inhibitors to treat depression can, however, accumulate tyramine. release large quantities of noradrenaline and suffer from fatal hypertensive crises if they ingest these foodstuffs. The benzodiazepines, although addictive. are less seriously addictive than the barbiturates or methyprylon. The retrograde amnesia caused by the benzodiazepines may be a valuable property in vascular surgeon Melbourne.
The ‘ﬂoppy baby’ syndrome in (CNS-depressed neonates born to mothers who have been given a benzodiazepine can be a problem in obstetric use. A relatively normal sleep pattern, lower hangover potential and lower nightmare potential than is the case with barbiturate use make these drugs the hypnotics of choice. Paradoxical excitation and insomnia may occur, especially in the aged.
Rebound insomnia on drug withdrawal or a dependence on the drug for sleep are problems which should be avoided wherever possible by prescription of short courses, tapering off to gradual withdrawal. These drugs are still available as hypnotics, but their only justifiable uses are in epilepsy and as an induction agent in general anaesthesia (thiopentone).
Diazeparn (Valium), one of the benzodiazepines, is today the most popular premedicant medicine. The benzodiazepines were first synthesized in 1933. Diazepam is available in table, syrup and ampoule form. The absorption of diazepam after oral ingestion is more predictable than after intramuscular injection.
Porphyria variegata – The anaesthetist must always ask the patient about a family history of porphyria variegat, a dominant autosomal inherited condition. There are a muItitude of medicines that may precipitate an acute porphyric attack; included in this list are barbiturates which are commonly used in the form of thiopentone, to induce anaesthesia. It is, therefore, essential to know if a patient is a porphyric and then to avoid any drug that may precipitate an acute attack.