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Biomedical subjects

M D Rawlins

Publications and source records attributed to M D Rawlins.

At least 181 records · Page 10Linked to original sources
PubMed1980

Pharmacokinetics, beta-adrenoceptor blockade and anti-hypertensive action of labetalol during chronic oral treatment.

1 beta-Adrenoceptor blockade, plasma labetalol concentrations and anti-hypertensive actions were investigated at 2 hourly intervals during the interdose period of chronic oral therapy in six hypertensive patients. 2 beta-adrenoceptor blockade varied during the inter-dose period and was maximal 2 and 4 h after the oral dose (P < 0.05). 3 Systolic pressure rose during the interdose period (P < 0.05). A significant correlation was found between the degree of beta-adrenoceptor blockade and the change in systolic pressure at 2 h after the oral dose. 4 Efficacy of labetalol as a beta-adrenoceptor antagonist and anti-hypertensive drug was assessed 2 h after an oral dose during chronic eight hourly dosage in sixteen hypertensive patients. Pharmacokinetics of labetalol were studied in the same patients. 5 Peak plasma labetalol concentration occurred 2 h after the oral dose and subsequently the plasma concentration declined monoexponentially. 6 The steady state concentration (CSS) of labetalol was correlated significantly with the daily oral dose in mg kg-1, the mid point labetalol concentration (Cmax+Cmin) divided by 2 and the isoprenaline dose ratio-1 at 2 h after the oral dose. 7 No correlation was found between the antihypertensive effect and the CSS ng ml-1 labetalol or between the isoprenaline dose ratio-1 and the CSS labetalol ng ml-1.

Administration, Oral↗
PubMed1980

Decreased epidermal aryl hydrocarbon hydroxylase and localized pustular psoriasis.

Microsomal aryl hydrocarbon hydroxylase (AHH) activity was measured in suction separated epidermis from forearm skin of thirteen patients with localized palmo--plantar pustular psoriasis and thirteen normal subjects before and after induction by benzanthracene. AHH activity had a mean value of 2 . 32 micrometer 30H-BP/mg microsomal protein/h +/- 0 . 23 (s.e.) in the patients and 3 . 41 +/- 0 . 23 in the normal subjects. AHH induction was also decreased with a mean value of 1 . 15 +/- 0 . 1 (s.e.) compared with 1 . 98 +/-- 0 . 14 for the normal subjects. Since in twelve of the patients the psoriasis had always been localized to the palms and soles, the decreased basal and induced AHH activity appears to be a primary characteristic of psoriatic skin; AHH activity initiate an increase in epidermal cell turnover through modulation of prostaglandin and adenylate cyclase activity.

Adolescent↗
PubMed1979

Factors affecting warfarin requirements. A prospective population study.

In 228 ambulatory patients receiving treatment with warfarin, there was a progressive decline in the dose required to produce an equivalent degree of anticoagulant control with increasing age from the third decade onwards. However, the relationship between age and dose was significant only in patients receiving warfarin after episodes of venous thromboembolism or because of coronary artery disease. Patient weight was also related to warfarin requirements, although it was less important a determinant than age.

Adult↗
PubMed1979

Psoriasis and cancer.

The incidence of skin cancer in patients with psoriasis seems to be low, despite repeated use of known carcinogens in treating the disorder. This may be due to a reduced capacity of psoriatic skin to metabolise precarcinogens because of impaired arylhydrocarbon hydroxylase (AHH) activity. If this hypothesis is correct, and impaired AHH activity in psoriatic skin is shared by other tissues, the incidence of cancers associated with environmental carcinogens may also be reduced in patients with psoriasis. Since the disease is probably genetically transmitted as a dominant trait, it may have persisted because it confers genetic advantage. This hypothesis, though speculative, provides a basis for further study.

Aged↗
PubMed1979

Activity of aryl hydrocarbon hydroxylase in psoriatic skin.

The activity of aryl hydrocarbon hydroxylase (A.H.H.), a microsomal mono-oxygenase, was reduced in epidermis from both the psoriatic lesions and clinically normal lesion-free skin from psoriatic patients. Induction of epidermal A.H.H. activity by benzanthracene was also significantly less than normal in both psoriatic lesions and in clinically normal skin from patients with psoriasis. The enzyme defect may be related to the primary genetic abnormality of the disease.

Adult↗
PubMed1979

Prazosin, pharmacokinetics and concentration effect.

The pharmacokinetics and effects of prazosin have been studied after intravenous and oral dosing (1 mg) to 6 normal male volunteers. The mean terminal (beta) half-life was 2.9 h after intravenous and oral routes. Oral bioavailability was 56.9%. The effects of prazosin on blood pressure were more pronounced after intravenous than oral administration, and the hypotensive effect greater on erect blood pressure. There was a significant correlation (P less than 0.02) between the fall in blood pressure and the plasma drug concentration after intravenous prazosin.

Administration, Oral↗
PubMed1979

The activity of aryl hydrocarbon hydroxylase in adult human skin.

1 Aryl hydrocarbon hydroxylase (AHH), a mixed-function oxidase system, has been identified in microsomal preparations of adult breast skin and foreskin. 2 Separation of dermis from epidermis by stretching, showed that AHH activity in human skin is almost exclusively located within the epidermis. 3 Preincubation of whole chopped skin with benzanthracene (5 muM to 100 muM) using a tissue culture system was accompanied by a concentration dependent increase in AHH activity. 4 Although there was no significant difference in AHH activity between the two sites, individuals differed markedly from one another in activity at any one site. Activity was observed to be positively correlated with age.

Adolescent↗
PubMed1979

Pharmacokinetics and pharmacodynamics of warfarin at steady state.

1 The relationship between warfarin dose, total and free plasma warfarin concentration, and anticoagulant effect was examined at several steady-state levels in fifteen patients during withdrawal of warfarin therapy. 2 Total plasma clearance was significantly correlated with the free fraction in plasma (r=0.955). 3 There was an age related decline in the dose of warfarin, and in the total and free plasma warfarin concentrations required to produce the same anticoagulant effect. However, neither total nor free plasma warfarin clearances varied with age. 4 Individual patients' log concentration-effect relationships were linear above a prothrombin ratio of 1.2 and there was a significant correlation (r=-0.586) between the slope and the free fraction of warfarin in plasma. It is suggested that plasma protein binding may reflect the interaction between warfarin and its effector site in the hepatocyte.

Anticoagulants↗