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Biomedical subjects

R Tozer

Publications and source records attributed to R Tozer.

8 recordsLinked to original sources

The arotinoids: early clinical experience and discussion of future development.

There has been great interest in the use of drugs attempting to modify the properties of malignant cells without necessarily destroying them. The family of compounds known as the retinoids have shown particular promise in this area. Current interest is directed towards established retinoids such as ATRA and 13-CRA. Newer synthetic retinoids such as fenretinide, the arotinoid Ro 40-8757, and 9-cis retinoic acid have been entering clinical trials. Ro 40-8757 is a particularly interesting new arotinoid with properties quite distinct from the other retinoids. It has different binding proteins and appears to regulate different genes than the classical retinoids such as ATRA or 13-CRA. Furthermore, it appears active against a different spectrum of malignancies. It also appears to have a relatively favourable side-effect profile. In addition to its anti-proliferative effects, this arotinoid may play a role in protection of bone marrow function after use of cytotoxic drugs. Development of Ro 40-8757 was halted before the compound had entered phase II testing due to lack of resources. Future developmental programmes for retinoids should move rapidly to explore the potential of interesting combinations identified in preclinical models. Retinoids should be considered primarily as drugs which modulate and enhance the effects of other active anticancer agents. Their development should not be prevented because they are unlikely to be active as single agents against common solid tumours.

Acitretin

The arotinoids: early clinical experience and discussion of future development.

There has been great interest in the use of drugs attempting to modify the properties of malignant cells without necessarily destroying them. The family of compounds known as the retinoids have shown particular promise in this area. Current interest is directed towards established retinoids such as ATRA and 13-CRA. Newer synthetic retinoids such as fenretinide, the arotinoid Ro 40-8757, and 9-cis retinoic acid have been entering clinical trials. Ro 40-8757 is a particularly interesting new arotinoid with properties quite distinct from the other retinoids. It has different binding proteins and appears to regulate different genes than the classical retinoids such as ATRA or 13-CRA. Furthermore, it appears active against a different spectrum of malignancies. It also appears to have a relatively favourable side-effect profile. In addition to its anti-proliferative effects, this arotinoid may play a role in protection of bone marrow function after use of cytotoxic drugs. Development of Ro 40-8757 was halted before the compound had entered phase II testing due to lack of resources. Future developmental programmes for retinoids should move rapidly to explore the potential of interesting combinations identified in preclinical models. Retinoids should be considered primarily as drugs which modulate and enhance the effects of other active anticancer agents. Their development should not be prevented because they are unlikely to be active as single agents against common solid tumours.

Animals

Antiepileptic drugs, hepatic enzyme induction and raised serum alkaline phosphatase isoenzymes.

Thirteen patients with epilepsy on long-term antiepileptic drug therapy and who had a persistently raised serum alkaline phosphatase (ALP) activity were investigated biochemically. Twelve patients had a raised liver ALP-isoenzyme activity and in nine of these the bone ALP-isoenzyme activity was normal. Gamma-glutamyl transferase (gamma GT) levels were raised in 12 patients. Two patients were hypoglycaemic. One patient fitted the biochemical parameters for subclinical osteomalacia. The resultant clinical picture showed 75% of patients with borderline hypocalcaemia, raised liver ALP, raised gamma GT and normal bone ALP activities in whom 1,25 dihydroxy-cholecalciferol (1,25-DHCC; vitamin D) therapy would be inappropriate, whilst 1,25-DHCC therapy might be considered for those with borderline hypocalcaemia and a raised bone ALP activity (three patients). No evidence was found of hepatotoxicity or drug induced cholestasis. It is considered that the induction of liver microsomal enzymes by antiepileptic drugs could include liver ALP (as opposed to bone ALP) as well as gamma GT and the inactivation pathways for 1,25 DHCC.

Adult

Comparison of the time course of the anorectic effect of fenfluramine and amphetamine with drug levels in blood.

Time courses of the suppressive effects on food intake of (+)-amphetamine and (plus or minus)-fenfluramine in deprived rats were found to be different. Amphetamine displayed a potent initial action which rapidly decayed, and this behavioural effect was consistent with the measured blood concentration of amphetamine which showed a peak at 1 h followed by rapid clearance. For fenfluramine, the initial suppression of eating was maintained over several hours and was, for the first hour, related to the blood concentration of fenfluramine but later to an active metabolite, norfenfluramine. The study shows how drug-induced changes in feeding behaviour fluctuate over time and illustrate how single measures of food intake may overlook information about the effectiveness of anorectic drugs.

Animals