Why does the blood brain barrier prevent some drugs from entering the brain?
·         The brain consumes over 20% of whole body's energy supply and nearly 15% of the blood of cardiac output. so the brain is one of the important organ and we know the complete body and other organ activity directly or indirectly controlled by the brain. so it is very necessary a barrier must be there to check unwanted chemicals/materials from the blood which is not suitable or harmful for the brain.[1]
·         same for few drugs, as prodrug (an inactive form of drug which converts into active drug after metabolism in body )and xenobiotics (a compound that is foreign to body) can be harmful to the brain so they prevent and blocked by the blood-brain barrier (BBB).
looking at chemical nature
·         Generally, the NON-LIPID SOLUBLE DRUG ( example-streptomycin, neostigmine, etc) don’t penetrate BBB while the LIPID-SOLUBLE DRUGS is able to cross BBB and have action central nervous system.
·         Dopamine is an important neurotransmitter /neurochemical that doesn’t enter the brain as it is a polar molecule.
in parkinsonism, dopamine concentration decreases. both levodopa and dopamine is part in drug mechanism, but dopamine can’t cross BBB while levodopa can cross BBB, so levodopa is given to the patient which further get convert into dopamine, beside an enzyme name monoamine oxidase (MAO) and few other don’t allow catecholamines,5-HT, etc to enter brain in active form.



Comments

Post a Comment

Popular posts from this blog

What is pharmaceutical formulation? What are the stages involved?

Image
Pharmaceutical formulation , in pharmaceutics, is a process in which various chemical substances, along with the active drug, are mixed to produce a final medicinal product. The word formulation is often used in a way that includes the dosage form used in the making. What Are The Stages And Timeline? Formulation studies include developing a preparation of the drug which is stable as well as acceptable to the patient. This usually involves adding the drug into a tablet or a capsule for administered drugs. It is important to differentiate that a tablet contains a variety of other potentially inert substances apart from the drug itself. Further, studies have to be done to ensure that the encapsulated drug is compatible with these other substances and will not cause harm, either direct or indirect. Preformulation stage in  pharma manufacturing  involves the characterization of a drug's physical, chemical, and mechanical properties to choose what other ingredients or excipients
Read more

How come supposedly dexamphetamine has a duration of action of only around 3 to 6 hours, while the expensive slow release version lisdexamfetamine has a duration of action of 12 hours, but 'lisdex' is converted to 'dex' within an hour?

Image
While, yes, it does take extra time for the body to convert it into amphetamine , it doesn't have much to do with the actual drug. This is adderall. It's comprised of 4 different amphetamine salts plus some inert binders to make it big enough to easily dispense and take. Your stomach acid will break down a pill in less than an hour. This is adderall XR. It's a 24 hour slow release. It contains pretty much the exact same mix of amphetamine salts. However, this is what is inside an adderall XR capsule. Those beads are the magic.  For more details regarding the conference please visit :  https://medicinalchemistryconferences.com/ Regards Ferruccio Steven | Program Manager | Pharmacology 2020 Larix International Pte Ltd Contact: +65 31655042 WhatsApp: +65 3158 6820 Email: pharmacology@medicinalchemistryconferences.com
Read more