Pulsatile Drug Delivery System : The Current Scenario

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Pulsatile drug delivery system (PDDS) are gaining importance as these systems deliver the drug at the right site action at right time and in right amount as per the pathophysiological need of the disease which enhances therapeutic activity of the drugs as well as decreases the adverse effects. The principle involved in PDDS is circadian cycle and one can treat the diseases which will exhibit circadian rhythm like asthma, peptic ulcer, cardiovascular diseases, arthritis, attention deficient syndrome in children, elevated body temperature, etc. PDDS can be classified into different varieties based on the mechanism responsible for delivery of the drug from the dosage form like time dependent PDDS, pH dependent PDDS, etc. The current review article focuses on the latest technological developments, formulation parameters, and release profiles of these systems.

Key words: PDDS, Circadian rhythm

Profile page link of the author: http://www.pharmainfo.net/arun-kumar-palle

Profile page link of the guide: http://www.pharmainfo.net/ramamohan

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Comments

G.Sailesh's picture

Nice work. Can all the drugs are suitable for desigining a pulsatile drug delivery system. Please give me some examples of drugs. How can you say that side effects of drugs can be reduced by this type of drug delivery system? On what basis the lag time is decided. Is there any general range of lag time? What happens if there is more lag time or very less lag time
Arun Kumar Palle's picture

Second you have asked some marketing products available A) 1) Theirform: (diclofenac) 2) PULSINCAP: (Dofetilide) 3) Innopram; XL tablets: (Verapamil HCl + Propranolol HCl ) 4) Covera-HS; XL tablets (Verapamil HCl) answer for next question is in next reply
Arun Kumar Palle's picture

third question you have asked is about less side effects? A) First when we revise about second generation delivery goal like sustained Release dosage form. The continuous exposure of the drug to body may lead to adverse effects. For example, diabetes mellitus requires chronic treatment with sustained release formulations of drugs like sulfonylurea which will damage the pancreas earlier than the corresponding immediate release dosage form. Second, drugs which exhibit tolerance should not be delivered at a constant rate, since the drug effect decreases with time at constant drug level. In addition drug toxicity increases with time when drug levels are held constant. In such cases it is preferable to opt for dosage form which will provide desired concentration of drug at particular time point only.
G.Sailesh's picture

I am very much satisfied with your answers. Waiting for the answers regarding lag time
Arun Kumar Palle's picture

Thanks for your compliments. And you have asked us a nice questions?. The answers for your question is some what lengthy so i will be giving you the answer in split parts. Initially you have asked that, whether this system is suitable for all the Drugs? A) Actually this system is in development and research stage. At present the studies on this system is based on formulation for treating diseases based on circadian cycle, chronological behavior like Cardiovascular Diseases/ BP is at it's lowest during the sleep cycle and rise steeply during early morning awakening period./ So for this type we can use Ca channel blockers. Asthma:/ Precipitation of attacks during night or at early morning hours/ so we can use Beta2 Agonist, anti histaminics. and some other like peptic ulcer ( hcl secretions), Diabetes ( Decrease insulin levels )etc. Now iam giving you the reply for your question? Some of the drugs formulated are Verapamil hcl, propranolo hcl, Diclofenac sodium, Dofetilide etc. However this system is in development stage we could not expect this system for each and every drug. But this system is successful for most of the drugs, vaccines. and iam continuing my answer in next reply
G.Sailesh's picture

Can we apply this concept to each and every drug? I mean other than the diseases that follow chronological behavior or circadian cycle. If so, please explain
Arun Kumar Palle's picture

Very nice question. we can extend this system apart form chronological behavior also. I think you have seen a general schematic diagram in our presentation.In order to activate the system a stimuli is needed this stimuli can be from internal or external. For example 1)In case of Diabetes mellitus there is rhythmic increase in the levels of glucose in the body, requiring injection of the insulin at proper time. For this disease we will design in such a way such that system includes pH sensitive hydrogel containing glucose oxidase immobilized in the hydrogel. When glucose concentration in the blood increases glucose oxidase converts glucose into gluconic acid which changes the pH of the system. This pH change induces swelling of the polymer which results in insulin release. Insulin by virtue of its action reduces blood glucose level and consequently gluconic acid level also gets decreased and system turns to the deswelling mode thereby decreasing the insulin release. 2) Inflammation: During inflammation, hydroxyl radicals are produced from these inflammation-responsive cells. Now we will design a system with hyaluronic acid which is specifically degraded by the hyaluronidase or free radicals. When we incorporate anti inflammatory drug into hyaluronic acid and administered at site of inflammation then HA degrades and release drug. 3) In some other case we will incorporate the drug into a polymer matrix which is sensitive for ultrasonic waves. When ultrasonic waves are applied they causes the erosion of the polymeric matrix thereby modulating drug release. As i have said previously every drug delivery system cannot fit to all the drugs.
Arun Kumar Palle's picture

Thanks for your compliments. Your question was about lag time. A) First coming to the lag time, it is the period where the drug is not released from this system followed by rapid drug release. In other words, it is required that the drug should not be released at all during the initial phase of dosage form administration. The lag time is decided based study on many factors like 1)Many body functions that follow circadian rhythm, i.e, their activity waxes and wanes with time. A number of hormones like rennin, aldosterone, and cortisol show daily fluctuations in their blood levels. Circadian effects are also observed in case of pH and acid secretion in stomach, gastric emptying, and gastro-intestinal blood transfusion. 2) Diseases like bronchial asthma, myocardial infarction, angina pectoris, rheumatic disease, ulcer, and hypertension shows time dependence.For example Some of the reports state that there is sharp increase in asthmatic attacks during early morning hours.For this type a drug delivery system is designed, which when administered at bedtime should releasing drug well after the time of administration i.e (during morning hours). Based up on some of these studies we will decide the lag time for each and factor. By this study we will decide the formulation parameters like Tablet type: Thickness of external coating, osmotic active agents, no of multicoated particulates (beads, pellets, granules, etc.) made of one or more populations of beads. Except an immediate release bead, whether the controlling bead need at least two coated membrane barriers or not. If yes then One of the membrane barriers is composed of an enteric polymer while the second membrane barrier is composed of a mixture of water insoluble polymer and an enteric polymer etc. Capsule type: Semipermeable membrane thickness, point of insertion of plug, length of plug inserted, osmotic active substance etc. These parameters effect the lag time. The decision whether lag time is less or more is decided by above said parameters. If the requirement is more lag time but the preparation is of less lag time then it is of no use and equal to the conventional systems.
Anil kumar appapurapu's picture

Abstract: Pulsatile drug delivery system (PDDS) are gaining importance as these systems deliver the drug at the right site action at right time and in right amount as per the pathophysiological need of the disease which enhances therapeutic activity of the drugs as well as " decreases the adverse effects." E1)Common mechanisms of ADR causes are: * Abnormal pharmacokinetics due to o genetic factors o comorbid disease states * Synergistic effects between either o a drug and a disease o two drugs Q1) can you clarify how these delivery will reduce the ADR? Q2) can be the Type B: Bizarre effects (or idiosyncratic)will also reduced Q3) any drugs is reported so far for this activity

anilkumar

Arun Kumar Palle's picture

Thank for your questioning. Before answering to your first question. When we consider in sustained release dosage form the drug is released for prolonged time continuously which has so many disadvantages due to continuous exposure. Now coming to the question it not actually adverse drug reaction we thought of mentioning less adverse effects or less side effects why because >The continuous exposure of the drug to body may lead to adverse effects. For example, diabetes mellitus requires chronic treatment with sustained release formulations of drugs like sulfonylurea which will damage the pancreas earlier than the corresponding immediate release dosage form. >Second, drugs which exhibit tolerance should not be delivered at a constant rate, since the drug effect decreases with time at constant drug level. >In addition drug toxicity increases with time when drug levels are held constant. In such cases it is preferable to opt for dosage form which will provide desired concentration of drug at particular time point only.When you could see a graph in our presentation you could come to clear picture about it. I could not completely get your second question and i hope the third question is also linked with it. Can you please specify me in clear.
Sandeep Reddy's picture

1)weather PDDS is used in the treatment of parkinsonism disease ? 2)effect of gastric enzymes on pulsatile capsule?
Arun Kumar Palle's picture

Very nice question. you have asked me about parkinsonism disease. I have to first mention you that this system is not completely established one, it is still in R&D level and upto now the treatment for parkinsonism using PDDS is in research only. In feature we could expect a good news. Next you have mentioned about Gastric enzymes Mainly in our presentation you could see the different systems like rupturable, erodible, osmotic based, pH etc. These systems designed as using mainly specific type of polymers, external coating, Osmotic ally active agents etc. These have a little bit effect by gastric enzymes but could not completely challenge the system.
Sandeep Reddy's picture

hi friend nice answering 1)how much quantity of the drug is incorporated in one pulsatile capsule?
Anil kumar appapurapu's picture

good reply what is adverse effect of a drug? yes the continuous exposure of the drug (dose) to body may lead to adverse effects my question Q2)is can be the Type B: Bizarre effects (or idiosyncratic)means occurrence of adverse effects i.e Dose in-depended ( drug dependent) in this connection also is this delivery is use full Q3) if 2nd is +ve to which drugs adverse effects reduced (reported?

anilkumar

Abhishek Rathi's picture

Dear Arun, Good presentation. Patent is available (Recent Pat Drug Deliv Formul. 2009;3(1):64-70.)where Site specific chronotherapeutic drug delivery systems was described. Can you elaborate its mechanism of action? Regards

Abhishek Rathi

Arun Kumar Palle's picture

Very nice question. Your question was about site targeted drug delivery by PDDS A) Inorder to expalin you the answer first i wnt to introduce one of the recent PDDS technology named PULSINCAP. This dosage form releases its drug content at either a predetermined time or at a specific site (e.g.,colon) in the gastrointestinal tract. The drug formulation is contained within a water-insoluble capsule body and is sealed with a hydrogel plug. Upon oral administration, the capsule cap dissolves in the gastric juice and the hydrogel plug swells. At a controlled and predetermined time point,the swollen plug is ejected from the dosage form and the encapsulated drug is released. I'am mentioning some of these for colon targeted drug delivery Biodegradable polymers coating/// Degradation of the polymer due to the action of the colonic bacteria releases the drug pH sensitive polymers coating/// Formulation coated with enteric polymers release the drug when formulation reaches down towards the alkaline pH range in the intestine Timed released systems/// Formulation is designed such that the drug releases after a lag time of 3-5 h that is equivalent to small intestinal transit time Bioadhesive systems/// Formulation coated with bioadhesive polymers that selectively provides adhesion to the colonic mucosa release the drug in the colon
Abhishek Rathi's picture

Thanks Arun for the Answer.

Abhishek Rathi

Pooja Chowdary's picture

Hello Arun, Your presentation appears terse , yet it is clear. 1) What are the various types of materials with which erodible coating layers are made? 2) what should be their ideal characteristics? 3) Do compatability problems exist between the coating material and drug?

pooja

Arun Kumar Palle's picture

spray dried lactose microcrystalline cellulose croscarmellose sodium ethylcellulose poly(lacticacid) (PLA) citric acid sodium bicarbonate poly(lactide-co-glycolide) (PLGA) poly(N-isopropylacrylamide) (PIPAAm) N,Ndimethylaminoethyl methacrylate chitosan polyol copolymer of acryl amide and allyl glucose hyaluronic acid (HA) cellulose acetate phthalate polyacrylates sodium carboxymethylcellulose Eudragit E-100 Hydroxypropylmethylcellulose phthalate Hydroxypropylmethylcellulose acetate succinate
Arun Kumar Palle's picture

The ideal properties depends up on several parameters Iam explaining one with an example During inflammation, hydroxyl radicals are produced from these inflammation-responsive cells.So during this Haluronic acid was used which degrades due to the free radicals. when drug is incorporated in HA, which responded to the hydroxyl radicals and degraded in a limited manner. Thus here drug release is achieved due to stimuli from free radicals. Here the parameter is the system should be sensitive to free radical. Similarly several parameters include like Glucose responsive pH sensitive Microorganism sensitive Temperature sensitive light sensitive Ultra sound sensitive magnetism sensitive etc For all these parameters to achieve combination of materials are used
Arun Kumar Palle's picture

Yes there are incompatibilities in every systems, but these are rectified during preformulations only.
Anil kumar appapurapu's picture

good presentation, here the power point questions 1. slide.no.3: in what cases short time drug release is benefit? is it follow zero order release? 2. slide.no.6: In general pulsatile are called time-controlled as the drug released is independent of the environment? If so pls explain 6 th slide? 3. slide.no.9: In Single unit pulsatile systems, for Capsule based systems: A swellable hydrogel plug was used to seal the drug contents into the capsule body . When this capsule came in contact with the dissolution fluid, it swelled; and after a lag time, the plug pushed itself outside the capsule and rapidly releases the drug. "Is there any problem related to dose dumping"? 4. slide.no.13: 13. Drug delivery system with eroding or soluble barrier coating, system consists of a core containing drug reservoir coated by a hydrophilic polymer HPMC. An additional enteric-coated film is given outside this layer to overcome intra-subject variability in gastric emptying rates what is the role of coating with hydrophilic polymer HPMC? 5. slide.no. 17, 18, 19: among the 3 external regulated systems which one is better and why? 6. slide.no: 25 how the beads of the system releases the drug? 7. slide.no. 26: is there any time specific requirement for dosing of drugs having specific absorption site in GIT, Colon through this system? thank you

anilkumar

Arun Kumar Palle's picture

The following are the conditions where short time drug release is beneficial >where the drug is subjected to large metabolic degradation. Due to 'first pass effect' there will be reduction in the bioavailability of the drug because, gradual release can result in greater degradation. >Secondly drugs with short half-life need to be administered repeatedly which results in patient non-compliance. >Further, in case of chronic treatment, where the drug is given in sustained release dosage form, continuous exposure of the drug to body may lead to adverse effect. >Lastly, drugs which exhibit tolerance should not be delivered at a constant rate, since the drug effect decreases with time at constant drug level. In addition drug toxicity increases with time when drug levels are held constant.
Anil kumar appapurapu's picture

chain questions for the answers: slide no 3 you mentioned short time drug release beneficial effects 1. is this type drug delivery overcomes 'first pass effect' ?if so then wt is the use of short time release for drugs subjected to large metabolic degradation? 2. is short time drug release reaches minimum effective concentration and maximum safety concentrations of the drug? 3. is short time drug release effects, equal with that of controlled release effects of a particular drug? 4. pls write a note on quotated note" Drug tolerance"?

anilkumar

Arun Kumar Palle's picture

The pulsatile system is not only time controlled one. I suggest you to first review the slide 5 where you can find the general mechanism of PDDS. This system requires stimuli to activate the system. The stimuli can be an external one or an internal one.
Anil kumar appapurapu's picture

chained questions for the answers pls go through in slide no 5 u mentioned only the classification of PPDS ? in slide no 6 you mentioned the mechanism 1. what factors that can stimuli to activate the system? 2. can you pls specify external and internal stimulator?

anilkumar

Arun Kumar Palle's picture

The external and internal factors cause the stimuli The internal factors like free radicals Hcl secretions hyperglycemic conditions External factors like Magnetism ultrasound irradiation
Arun Kumar Palle's picture

There is no chances of dose dumping. This system contain release controlling plug between immediate release compartment and pulsed release compartment. On contact with aqueous fluids,the cap rapidly dissolves thereby releasing the immediate release component followed by pulsed release component. The lag time is provided by the plug which is inserted in to the body.
Anil kumar appapurapu's picture

1. can you pls explain the factors leading to dose dumping? 2. is it depends on drug nature or delivery type or both?

anilkumar

Arun Kumar Palle's picture

The answer for both of questions is one The dose dumping is generally due to the system, drug and also any defect in final formulation like Improper coating of external rupturable coating.
Arun Kumar Palle's picture

hydrophilic swellable polymeric coating of HPMC which is capable of delaying the drug release through slow interaction with aqueous fluids
Anil kumar appapurapu's picture

in generally HPMC is applications are wide range 1. what concentration is preferable? 2. what chemical moiety of HPMC is responsible for the delaying the drug release through slow interaction with aqueous fluids

anilkumar

Arun Kumar Palle's picture

every external regulated system has it's own features. One over comes other. and one more is also present Microelectromechnical systems. But Magnetic was foun d to be the leading
Abhishek Rathi's picture

Dear Arun, I have some queries, In Externally Regulated Systems, 1.In case of magnetic field regulated system what should be the strength of magnetic field applied? 2.In case of Irradiation system which is the light source to be used for irradiation?

Abhishek Rathi

Abhishek Rathi's picture

Dear Arun, In case of Oral Time Controlled Pulsatile Technology, which are the controlled release polymers used? 1.In SODAS, 2.In CODAS, 3.In DIFFUCAPS.

Abhishek Rathi

Abhishek Rathi's picture

Dear Arun, In case of the Oral Time Controlled Pulsatile Technology,there are many methods available like SODAS, CODAS, PRODAS, MXDAS, DUREDAS, DIFFUCAPS which one is widely used? Which drugs could be administered by applying this method?

Abhishek Rathi

Arun Kumar Palle's picture

First coming to SODAS Based on the production of controlled release beads, the SODAS(r) technology is characterised by its inherent flexibility, enabling the production of customised dosage forms that respond directly to individual drug candidate needs. Benefits offered by the SODAS(r) technology include: >controlled absorption with resultant reduction in peak to trough ratios >targeted release of the drug to specific areas within the gastrointestinal tract >absorption independent of the feeding state >suitability for use with one or more active drug candidate >facility to produce combination dosage forms >"sprinkle dosing" by administrating the capsule contents with soft food >once or twice daily dose resembling multiple daily dose profiles Products marketed using the SODAS(r) Technology SODAS(r) technology is a proven system approved by regulatory authorities. The most recent U.S. regulatory approvals for SODAS(r) based drugs include a differentiated once daily morphine product (Avinza(r)), an extended release formulation of methylphenidate with a bi-modal release profile (Ritalin(r) LA), an extended release formulation of dexmethylphenidate hydrochloride also with a bimodal release profile (Focalin(r) XR) and a once daily fluvoxamine maleate extended release capsule (Luvox(r) CR).
Arun Kumar Palle's picture

Second CODAS Benefits offered by the CODAS(r) technology include: >delivery profile designed to compliment circadian pattern >controlled onset, extended release delivery system >rate of release essentially independent of pH, posture and food >"sprinkle" dosing by opening the capsule and sprinkling the contents on food >reduction in effective daily dose and drug exposure >gastrointestinal tract targeting for local effect >reduced systemic exposure to achieve a target profile Products Verelan(r) PM represents a commercialised product using the CODAS(r) technology. This once daily version of the cardiovascular compound verapamil hydrochloride product provides therapeutic concentrations in the morning hours to correlate with normal circadian rises in blood pressure in the early morning. It is currently marketed in U.S.
Arun Kumar Palle's picture

Third MXDAS MatriX Drug Absorption System (MXDAS(r) Technology), formulates drug in a hydrophillic matrix, made up of a proprietary blend of polymers, which controls the drug's rate of release through a process of diffusion and erosion in the gastrointestinal tract. The release of drug from this system is a dynamic process, comprised of polymer wetting, polymer hydration, and polymer dissolution. >Upon contact with fluid of the gastrointestinal fluids, the tablet surface wets and the hydrophilic polymer begins to partially hydrate, forming a hydrated gel layer around the tablet. >Expansion of the gel layer occurs as fluid permeates into the tablet, increasing the thickness of the gel layer, allowing drug to diffuse out through this layer. >Tablet erosion occurs when the outer layer becomes fully hydrated and is released into the gastric fluids. Water permeates toward the tablet core concurrently. >Soluble drug is released largely by diffusion from the gel layer and by exposure through tablet erosion. Benefits offered by the MXDAS(r) technology include: >controlled absorption over a period >targeted delivery to absorption sites >simple process for controlling release of drug substances >can be formulated using conventional equipment and processing methods >robust formulation, highly resistant to release inconsistencies and dose dumping >flexible range of profiles achievable Some of the drugs: isosorbide mononitrate, dalfampridine. This sytem is submitted for patents so i could not give information.
Arun Kumar Palle's picture

Next PRODAS Programmable Oral Drug Absorption System (PRODAS(r) Technology) is a multiparticulate technology, which is unique in that it combines the benefits of tabletting technology within a capsule. Benefits offered by the PRODAS(r) technology include: >multi-unit system, which allows customised release and absorption patterns >equivalent bioavailability to reference multiple dose product in a once daily formulation >minimum peak to trough ratio at steady state >minimal food impact >pulsed / programmed release to different sites in the GI tract >combines tabletting technology with multi-unit features >tablet efficiency >process control >functional coating(s) The PRODAS(r) delivery system is presented as a number of minitablets combined in a hard gelatin capsule. Very flexible, the PRODAS(r) technology can be used to target the profile of a candidate drug. It is possible to incorporate different minitablets, each one formulated individually and designed to release drug at different sites so that higher dose loading is possible within the gastrointestinal tract. It is also possible to incorporate minitablets of different sizes so that high drug loading is possible. PRODAS(r) technology, by incorporating minitablets with different release rates, can display the characteristics of a number of different conventional dosage forms: immediate release component to mimic the onset of a conventional tablet form ensuring that the once daily formulation is as fast acting delayed release component for site/regional release and/or food resistance sustained release component for additional controlled release/profile extension
Arun Kumar Palle's picture

Elan Drug Technologies' DUal RElease Drug Absorption System (DUREDAS(tm) Technology) is a bilayer tablet which can provide immediate or sustained release of two drugs or different release rates of the same drug in one dosage form. The tabletting process can provide an immediate-release granulate and a modified-release hydrophilic matrix complex as separate layers within the one tablet. The modified-release properties of the dosage form are provided by a combination of hydrophilic polymers. Benefits offered by the DUREDAS(tm) Technology include: >bilayer tabletting technology >tailored release rate of two drug components >capability of two different CR formulations combined >capability for immediate release and modified release components in one tablet unit dose, tablet presentation The DUREDAS(tm) system can easily be manipulated to allow incorporation of two controlled release formulations in the bilayer. Two different release rates can be achieved from each side. In this way greater prolongation of sustained release can be achieved. Typically an immediate release granulate is first compressed followed by the addition of a controlled release element which is compressed onto the initial tablet. This gives the characteristic bilayer effect to the final dosage form. A further extension of the DUREDAS(tm) technology is the production of controlled release combination dosage forms whereby two different drugs are incorporated into the different layers and drug release of each is controlled to maximise the therapeutic effect of the combination. Again both immediate release and controlled release combinations of the two drugs are possible. A number of combination products utilising this technology approach have been evaluated. Drug example: pseudoephedrine
Arun Kumar Palle's picture

Diffucaps is a multiparticulate bead system comprised of multiple layers of drug, excipients, and release-controlling polymers. The beads contain a layer of organic acid or alkaline buffer to control the solubility of a drug by creating an optimal pH microenvironment for drugs that exhibit poor solubility in intestinal pH, in environments with pH greater than 8.0, or in physiological fluids.. Alternatively, the beads can contain a solid-solution of drug and crystallization inhibitor to enhance bioavailability by maintaining the drug in its amorphous state. Diffucaps technology is especially suitable for drugs that traditionally require multiple daily doses or drugs needing customized release formulations. Each Diffucaps bead has an inert core surrounded by drug and coated with a functional polymer membrane to control the rate of drug release. Diffucaps beads are Ideal for drugs exhibiting poor solubility in lower intestinal pH, in environments with pH above 8.0, or in physiological fluids >Can combine multiple drugs and/or multiple release profiles in the same dosage form >Simple formulation of dose-proportional strengths. >Can minimize food effect products: INNOPRAN XL - marketed in the U.S. by GlaxoSmithKline
Abhishek Rathi's picture

Dear Arun, I have seen your answers to my questions,but all of my questions are still unanswered.Priorly I visited the the website of Elan Drug Technologies but couldn't find the answers there, I just want to know following. My questions were, Que 1.In case of Oral Time Controlled Pulsatile Technology, WHICH are the CONTROLLED RELEASE POLYMERS used? 1.In SODAS, 2.In CODAS, 3.In DIFFUCAPS. Que 2.In case of the Oral Time Controlled Pulsatile Technology,there are many methods available like SODAS, CODAS, PRODAS, MXDAS, DUREDAS, DIFFUCAPS which one is widely used?

Abhishek Rathi

Abhishek Rathi's picture

My other question, In Externally Regulated Systems, 1.In case of magnetic field regulated system what should be the strength of magnetic field applied? 2.In case of Irradiation system which is the light source to be used for irradiation?

Abhishek Rathi

Arun Kumar Palle's picture

frequency 55kHz and amplitude 40 kA/m.
Abhishek Rathi's picture

Thanks for the answers

Abhishek Rathi

Arun Kumar Palle's picture

radiation around 488 nm. But this is restricted to some parts of body only.
Abhishek Rathi's picture

What is the light source used???

Abhishek Rathi

Arun Kumar Palle's picture

I want to explain you this with an example of mechanism The general mechanism In this the drug+nano shells+hydrogels are formulated.when exposed to near-infrared light, the nano shells absorb the light and convert it to heat, raising the temperature of the composite hydrogel above its LCST. This in turn initiates the thermoresponsive collapse of the hydrogel, resulting in an increased rate of release ofs oluble drug held within the polymer matrix.
Arun Kumar Palle's picture

God question Here Iam attaching you the answers

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