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Biomedical subjects

M I Robertson

Publications and source records attributed to M I Robertson.

7 recordsLinked to original sources
PubMed1999

Regulatory issues with excipients.

The history of the regulatory control of pharmaceutical ingredients is briefly reviewed. The impact of legislation, its interpretation through European and international guidelines and resulting licensing policies are discussed. The important role played by excipients in modern formulations is recognised and some examples are given of the unexpected consequences of inappropriate choices. Some data are provided on the extent to which excipients and active ingredients appear in UK-licensed medicines and on the reference standards (pharmacopoeial and non-official) used to control the excipients.

Drug Stability↗
PubMed1976

Effects of alpha-methyldopa on blood pressure in the anaesthetized dog.

Intravenous infusion over 1 h of 20 mg kg(-1) of alpha-methyldopa produced hypotension in the anaesthetized dog. The magnitude of this effect was, however, inversely correlated with bodyweight. Either rapid intravenous injection of alpha-methyldopa or slow infusion of alpha-methyldopate, was less effective in lowering blood pressure than infusion of free alpha methyldopa in dogs of equivalent bodyweight. Infusion of alpha-methyldopa into a vertebral or internal carotid artery produced hypotensive responses but these were no greater and generally less than those obtained to intravenous infusion. alpha-Methyldopa was therefore capable of producing hypotension in the dog but no evidence was obtained for this being the result of an action within the brain.

Animals↗
PubMed1970

Selective depletion of noradrenaline: a proposed mechanism of the adrenergic neurone-blocking action of bretylium.

1. The effects of bretylium have been investigated on the content and sub-cellular distribution of noradrenaline in cat spleen and on the overflow of noradrenaline in response to stimulation of the splenic nerve.2. Bretylium, 15 min after its administration, produces a significant depletion of noradrenaline in only the supernatant fraction of an homogenate; at this time adrenergic neurone blockade is evident. This depletion of noradrenaline is apparent up to 18 h later but has disappeared 7 days after the administration of bretylium when nerve function is also restored.3. Both the development of the neurone blockade and the depletion of noradrenaline are prevented by previous administration of (+)-amphetamine.4. In bretylium-pretreated cats the noradrenaline content of the supernatant fraction is replenished and the neurone blockade is abolished after treatment with (+)-amphetamine.5. The depletion of noradrenaline, which is evident 30 min, 60 min and 18 h after treatment with bretylium, from other subcellular fractions-especially the high-speed particulate fraction-appears to be unassociated with adrenergic neurone blockade.6. It is concluded that bretylium produces its adrenergic neurone-blocking activity by depleting noradrenaline from a "store" whose amine appears in the supernatant fraction after homogenization. Whilst bretylium is present this "store" cannot refill with noradrenaline.

Amphetamine↗