Transdermal delivery of insulin by amidated pectin hydrogel matrix patch in streptozotocin-induced diabetic rats: effects on some selected metabolic parameters.

Studies in our laboratory are concerned with developing optional insulin delivery routes based on amidated pectin hydrogel matrix gel. We therefore investigated whether the application of pectin insulin (PI)-containing dermal patches of different insulin concentrations sustain controlled release of insulin into the bloodstream of streptozotocin (STZ)-induced diabetic rats with concomitant alleviation of diabetic symptoms in target tissues, most importantly, muscle and liver.Oral glucose test (OGT) responses to PI dermal matrix patches (2.47, 3.99, 9.57, 16.80 µg/kg) prepared by dissolving pectin/insulin in deionised water and solidified with CaCl2 were monitored in diabetic rats given a glucose load after an 18-h fast. Short-term (5 weeks) metabolic effects were assessed in animals treated thrice daily with PI patches 8 hours apart. Animals treated with drug-free pectin and insulin (175 µg/kg, s.c.) acted as untreated and treated positive controls, respectively. Blood, muscle and liver samples were collected for measurements of selected biochemical parameters.After 5 weeks, untreated diabetic rats exhibited hyperglycaemia and depleted hepatic and muscle glycogen concentrations. Compared to untreated STZ-induced diabetic animals, OGT responses of diabetic rats transdermally applied PI patches exhibited lower blood glucose levels whilst short-term treatments restored hepatic and muscle glycogen concentrations. Plasma insulin concentrations of untreated diabetic rats were low compared with control non-diabetic rats. All PI treatments elevated plasma insulin concentrations of diabetic rats although the levels induced by high doses (9.57 and 16.80 µg/kg) were greater than those caused by low doses (2.47 and 3.99 µg/kg) but comparable to those in sc insulin treated animals.The data suggest that the PI hydrogel matrix patch can deliver physiologically relevant amounts of pharmacologically active insulin.A new method to administer insulin into the bloodstream via a skin patch which could have potential future applications in diabetes management is reported

The effect of transdermally delivered OA (TD OA) alone and in combination with CHQ (CHQ-OA) on hepatic and gastrocnemius glycogen concentrations of <i>P</i>. <i>berghei</i>-infected rats in comparison with control animals (NIC and IC).

<p>The effect of transdermally delivered OA (TD OA) alone and in combination with CHQ (CHQ-OA) on hepatic and gastrocnemius glycogen concentrations of <i>P</i>. <i>berghei</i>-infected rats in comparison with control animals (NIC and IC).</p

The effect of transdermally delivered OA (TD OA) alone and in combination with CHQ (CHQ-OA) on body weight, food and water intake in <i>P</i>. <i>berghei</i>-infected rats in comparison to control animals (NIC and IC).

<p>The effect of transdermally delivered OA (TD OA) alone and in combination with CHQ (CHQ-OA) on body weight, food and water intake in <i>P</i>. <i>berghei</i>-infected rats in comparison to control animals (NIC and IC).</p

Comparison of the short-term effects of oral administration of OA (O OA), transdermal application of OA (TD OA) and CHQ-OA (TD CHQ-OA) pectin matrix patches with respective controls and a standard drug CHQ (D) on plasma insulin concentrations in <i>P</i>. <i>berghei</i>-infected rats with non-infected (NIC) and infected control (IC) animals.

<p>Values are presented as means, and vertical bars indicate SEM of means (n = 30 in each treatment group).^⋆p˂0.05 by comparison with non-infected control (NIC) animals, ^♦p˂0.05 by comparison with infected control (IC) animals, ^∞p˂0.05 by comparison with CHQ (O CHQ) treated animals.</p

Acute effects of different antimalarial formulations on plasma insulin concentrations in non-infected (A) and <i>P</i>. <i>berghei</i>-infected (B) rats following a 4-hour glucose tolerance test.

<p><b>The blood samples were collected 4 hours after treatment.</b> Values are presented as means, and vertical bars indicate SEM of means (n = 6 in each treatment group).^⋆p˂0.05 by comparison with non-infected control (NIC) animals, ^♦p˂0.05 by comparison with infected control (IC) animals, ^∞p˂0.05 by comparison with CHQ (O CHQ) treated animals.</p

The Effects of Transdermally Delivered Oleanolic Acid on Malaria Parasites and Blood Glucose Homeostasis in <i>P</i>. <i>berghei</i>-Infected Male Sprague-Dawley Rats

<div><p>The present study investigated the effects of transdermally delivered oleanolic acid (OA) monotherapy and in combination with chloroquine (CHQ) on malaria parasites and glucose homeostasis of <i>P</i>. <i>berghei</i>-infected male Sprague-Dawley rats. Oral glucose test (OGT) responses to OA-pectin patch and CHQ-OA combination matrix patch were monitored in non-infected and infected rats. To evaluate the short-term effects of treatment, percentage parasitaemia, blood glucose, glycogen and plasma insulin were monitored in separate groups of animals treated with either OA-patch monotherapy or CHQ-OA combination pectin patch over a 21-days period. Animals treated with drug-free pectin and CHQ acted as untreated and treated positive controls, respectively. Infected control rats exhibited significantly increased parasitaemia which was accompanied by hypoglycaemia. Both OA monotherapy and CHQ-OA combination therapy reduced and cleared the malaria parasites within a period of 4 and 3 days, respectively. Compared to respective controls groups, OGT responses of animals treated with OA monotherapy or CHQ-OA combination therapy exhibited lower blood glucose levels at all time points. A once-off transdermal application of OA-patch or CHQ-OA combination patch significantly improved blood glucose concentrations inducing any changes in insulin concentration. Transdermal OA used as a monotherapy or in combination with CHQ is able to clear and reduce the malaria parasites within a shorter period of time without eliciting any adverse effects on glucose homeostasis of <i>P</i>. <i>berghei</i>-infected rats.</p></div

H and E stains illustrating the effects of OA-containing dermal patches on the morphology of the skin.

<p>Picture (6A) represents intact secretory ducts (ISD), uninjured stratum basale (USB) and intact sebaceous glands (ISG) of the non-infected control animals (Mag 7×500 μm). Picture 6B represents intact secretory ducts, uninjured stratum basale and intact sebaceous glands of the <i>P</i>. <i>berghei</i>-infected control (Mag 7×500 μm).Treatment with oral CHQ picture 6C (Mag 7×500 μm) and OA dermal patches picture 6D (Mag 8×500 μm) showed intact secretory ducts, uninjured stratum basale and intact sebaceous glands.</p

Comparisons of OGT responses in non-infected [A] and <i>P</i>. <i>berghei</i>-infected rats [B] to different antimalarial formulations with respective control animals.

<p>Values are presented as means, and vertical bars indicate SEM of means (n = 6 in each treatment group). ^⋆p˂0.05 by comparison with non-infected control animals (NIC), ^♦p˂0.05 by comparison with infected control (IC) animals and ^∞p˂0.05 by comparison with CHQ treated animals (O CHQ).</p

Comparison of the effects of oral administration of OA (O OA), transdermal application of OA (TD OA) and CHQ-OA combination (TD CHQ-OA) pectin matrix patches on blood glucose concentrations with those of respective controls and a standard drug CHQ (O CHQ).

<p>Values are presented as means, and vertical bars indicate SEM of means (n = 30 in each treatment group). ^⋆p˂0.05 by comparison with non-infected control animals (NIC), ^♦p˂0.05 by comparison with infected control animals (IC), ^∞p˂0.05 by comparison with CHQ treated animals (O CHQ), ^■p˂0.05 by comparison with oral OA treated animals (O OA), ^#p˂0.05 by comparison with transdermal OA treated animals (TD OA) and ^●p˂0.05 by comparison with CHQ-OA <b>treated</b> animals (TD CHQ-OA).</p

The effects of oral administration of OA (O OA), transdermal application of OA (TD OA) and CHQ-OA (TD CHQ-OA) pectin matrix patches on percentage parasitaemia in <i>P</i>. <i>berghei</i>-infected rats.

<p>Values are presented as means, and vertical bars indicate SEM of means (day 0, n = 30; day 7, n = 24; day 9, n = 18; day 12, n = 12; day 21, n = 6). ^⋆p˂0.05 by comparison with control animals.^∞p˂0.05 by comparison with oral CHQ treated animals.</p