PHARMACOKINETICS IN NOVEL DRUG DELIVERY DESIGN-1
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The fate of a chemical entity or a drug after its administration can be divided into two phases: pharmacokinetic and pharmacodynamic. The pharmacokinetic phase is the temporal relationship between the observed drug concentration (generally in plasma, serum or whole blood; ideally the concentration at site of action is of consequence, but this may be difficult or, in some cases, impossible to determine) and dose, drug delivery system characteristics, frequency of administration and the route of drug entry. The pharmacodynamic phase is the relationship between the observed drug concentration and the intensity or magnitude of the pharmacological effect.
The underlying assumption in studying the pharmacokinetic and pharmacodynamic characteristics of a drug is that the required pharmacological effect (or side-effect or toxicity) is a function of drug concentration. More correctly, the desired pharmacological effect will be observed within a range of drug concentrations referred to as the therapeutic window.
Drug concentrations below or above the therapeutic window will, therefore, show either no effect or exhibit untoward effects, respectively, thereby precipitating therapeutic failure. The therapeutically relevant drug concentrations may be specified by the Minimum Effective Concentration (MEC) and the Minimum Toxic Concentration (MTC) or for ease indicated by an average concentration that falls between the MEC and the MTC.
The ultimate goal of a drug delivery device, whether traditional or novel, should therefore be to attain and maintain drug concentrations within the therapeutic window or close to the average concentration, for the requisite duration, with minimum fluctuation, so as to obtain clinical success. In order to understand how this may be achieved for drug delivery systems designed to deliver drug systemically, one needs to have a basic understanding of concentration- time relationship/s after drug administration and their dependence on the drug delivery system, i.e., pharmacokinetics
I will continue this discusion in next blog....
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good..........keep blogging
good..........keep blogging
Supriya vavilapalli
THE COGNITIVE MOLECULES
http://www.pharmainfo.net/supriya-vavilapalli
Dear.. You have mentioned in
Dear..
You have mentioned in your blog that the ultimate aim of any drug delivery system is to deliver drug within the limitations of the therapeutic window....then how is this differently done in novel drug delivery system..please explain..
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Faria Zarrin
Team: BLOGBUSTERS
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http://www.pharmainfo.net/zarrinfaria/biography
My Team:
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Reply...
Dear Zarin Faria,
Traditional Drug delivery systems such as tablets, capsules, injections, parenterals or advanced drug delivery systems such as Transdermal systems or osmotic pumps send the drug into the blood and from the blood, drug is distributed into different tissues. In those tissues, where the receptors are there, action is changed, and where the receptors are not there the drug is either reversibly bound or eliminated. In this situation if the drug is available either less than or more than the levels indicating in the therapeutic window, sometimes activity is not seen and sometimes toxicity is seen.
When Novel Drug Delivery systems such as liposomes, nanoparticles or resealed erythrocytes are administered; very small amounts of drug are given because the drug is going directly to the receptors; they are given either bound or conjugated to a carrier. The entire dose is given into the blood and the blood is acting merely as a carrier/transport system. In fact Novel Drug Delivery systems such as liposomes and nanoparticles help to alter the known pharmacokinetics of the drug. The rate of metabolism and elimination are altered, hence the half life is altered, so the approach in NDDS is different. One such approach is given below:
A pegyllated and targeted(conjugated with aptamers) solid lipid nanoparticle (SLN) system of an anti-cancer drug containing glyceryl monostearate as a base is given as a colloidal suspension injection into blood; because of its hydrophilicity it escapes opsonisation and it will be traveling in the blood; this nanoparticulate-aptamer bioconjugate was targeted towards the PSMA markers on prostate tumor cells and because the tumor is having leaky capillary walls the SLNs will penetrate the tumor tissue; because the tumor usually has higher temperature than the rest of the body SLNs will melt there , the drug molecules connect with the receptor in the cancerous cells and destroy the cancerous cells. In this picture, drug does not got to the ordinary tissues.
Thus the approach of NDDS is different from the approach of traditional systems.
Regards,
Santosh Kumar. JH
Regards,
Santosh Kumar
Pharmacokinetics is very important.
Dear Santosh Kumar
You have taken a very important topic. Very good. The amount of drug available in the blood is an important issue because blood is the carrier and blood vessels are your channels that are like the irrigating canals; they supply the nutrients to the tissues and take away the wastes. So we use these channels to supply the drugs to the tissues. When a drug is administered into the body; how fast it is absorbed into the blood , how fast it is distributed from there to different tissues, how fast it is metabolised and how fast it is eliminated ---- the rates of these four processes-- and their discussion and dependence on other factors constitutes the study of pharmacokinetics. Very interesting and useful subject. It has many applications but its maximum use is in clinical pharmacy.
vijaya Ratna
http://www.pharmainfo.net/vijayaratna/biography
Nice to hear from you madam .....
Dear Madam,
Thank you for nourshing my blog with our words on pharmacokinetics, I will try my level best to make it more interactive and of application oriented.
Regards,
Santosh kumar
Regards,
Santosh Kumar
KISS-Keep it Simple and Sexy
You are saying like this
"Yada yada hi dharmasya glanir bhavati Bharata; Abhyutthanam adharmasya tadatmanam srijamyaham. Paritranaya sadhunam vinasaya cha dushkritam; Dharma-samthapanarthaya sambhavami yuge yuge."
only experts can understand.
You need to say like this
Whenever the balance of the universe is disturbed , For the protection of those who are in trouble, Lord Krish will reincarnate himself .
If you meet any great scientist , they talk in simple terms. They explain everything in simple launguage like in stories. That is possible only becuase they really mastered in it . That's why they explain the concepts in simple terms . ( Something like Pitta Katha lu)
Please try to learn that technique . You will have much much better future .
The time you are spending here should help building your career than spoil you. Hope you take in positive way ..
Thank you
Dear Sir,
Thank you sir for your enlightenment in me at the right time.As i have been doing competitions since January, i was a bit exhausted,but your words have brought up blossoms in my thoughts. Really you had been a Lord Krishna in my journey of this Skillsbharata.
Regards,
Santosh Kumar. JH
Regards,
Santosh Kumar
Skillsbharata - Good word
I think you are playing without game plan . It is like going to batting in cricket without any home work. You will be stressed out for each ball/over
Here,you just need to pick one topic a month. Need to collect information and present it in four parts ( one each week) . How hard it is ? just couple of hours work for month. Are you doing (playing) this way ? Please let me know if you need any help.