Pharmaceutical Products and Drug Action (The development of new synthetic…
Pharmaceutical Products and Drug Action
Medicine- a substance that improves health
Beneficial drugs that can either be natural or synthetic
Medicines have a therapeutic effect.
Drug- a chemical that affects how the body works
The body could change to be healthier or worst
Some drugs are illegal as it has a negative impact on the body
Administration of drugs
Depends on the chemical nature of the drug, the condition of the patient, and the most effective way for the drug to reach its target organ
Orally, through the mouth usually as tablets, pills and capsules
Inhaled, such as asthma patients, the drug is breathed in as vapor
Skin patch allow hormones to pass through skin directly to the blood
Suppositories, are drugs that are sent into the rectum usually for treatment of digestive illnesses
Eye or ear drops are drug solutions dropped directly to treat infections
Parenteral, are the common injections that can be injected into the muscle or blood stream and even under the skin for multiple purposes.
Bioavailability of drugs: the amount that reached the target
Not all drugs are taken by the target organ as some have been broken down through metabolic processes along the journey. Some may not even be absorbed into the blood stream.
Bioavailability is the fraction of the drug that reaches the target organ
Bioavailability is important to calculate how many dosage of drug a patient should consume.
There are a few factors that affect the bioavailability
Administration of the drug
Drugs taken orally have lower bioavailability due to the drug passing through the digestive system and the liver where enzymes can break them down before reaching the bloodstream.
Drugs that have a more direct route such as injection into the bloodstream have higher bioavailability.
As a result, drugs that are taken orally are taken at a dosage of four times higher.
Solubility of drugs
Water solubility is important for transport in the bloodstream
However, lipid solubility is important for transports through membranes during absorption.
Drugs that are more soluble in lipid have higher bioavailability.
Functional groups in drugs
1.The reactivity and solubilitu of drugs in different parts of the body is affected by the pH, either basic or acidic which will determine its charge.
Physiological effects of drugs are complex
Are unintended physiological effects which very from drugs and different people.
-Some side-effects are beneficial but some are bad causing drowsiness, nausea even heart burn.
-They are even drugs that can cause organ damage if not taken in consideration
Tolerance and addiction
When a person is given repeated doses of the same drug, the body can be used to it and the person becomes tolerant.
-when this occurs, the person may need to take higher doses of the drug or take a stronger drug.
-this may be due to the body being more conscious and abling it to break down more of the drug.
-it can also be caused by the receptor cells being less effective.
Addiction or dependence of a drug occurs when a patient becomes reliant on the drug in order to feel normal and suffer withdrawal symptoms if it is not taken.
-Symptoms can be mild or severe.
-The dosing regime for a drug is how much and how frequent a drug should be taken.
-Calculation of dosage must take bioavailability into account. As well as side-effects and potential problems such as tolerance or addiction. We also have to take age, sex and weight, diet and environment for some drugs.
-Therapeutic window is the range of concentration of drugs un the blood that is suitable. It should not be below (causing the drug to not be as effective) and not above (causing side-effects)
-The therapeutic window differs from drugs to drugs.
Therapeutic Index (TI)
-This is the ratio of dose that produces toxicity to the dose that produce clinically effective response in a polution.
ED50=effective doses, is a dose thaf produces therapeutic effects on 50% of the population
LD50=lethal dose, dose that is lethal to 50%of the population usually for animal trials. Animal TI calculated by LD50/ED50. The lethal dose is fixed.
TD50=toxic dose, dose that is toxic for 50%of the population usually used in human studies. HumanTI=TD50/ED50, toxic dose is the upper limit.
Higher TI means a bigger margin of doses that are effective meanwhile low TI, less margin of safety.
Drug Action Depends on Interactions with Receptors
Activity of drug is determined by the ability to bind to the specific receptor cells which are usually proteins, enzymes, chemical structures on cell membrane and the DNA.
The binding of drug prevents and inhibits the normal substrate to attach and interrupt the development of disease.
Chemical fit of the receptor and the drug is important.
the better the fit, the more effective the drug.
binding usually involves different types of bonds
The development of new synthetic drugs is a long and costly process
Demand for drugs is also because new viral strains of flu are newly discovered.
Pharmaceutical companies trying to find new drug that have less side effects and more effective.
The cost of making a drug is very pricey, thus investor focus on a specific purpose.
Usually, Pharmaceutical companies focus on making drugs for illnesses which are prevalent across the world as the profit of the selling could support the high amount of money that went into the research.
The process is very long and take 10-12 years.
In the past, researchers use a trial and error basis to find new drugs. Now however, rational drug design is focused on. Rational drug design is a basis of finding suitable molecule that binds to the specific receptor thus easily targeting the specific organ.
Once the molecule is identified,
Find the lead compound that corresponds to the desired pharmaceutical activity..
The lead compound is tested with analogues through a process called combinatorial chemistry which tests the effectiveness of the drug.
The potential medicine is then tested using animals under the strict legislative control. Ethical and economical reasons pursue testing animals to a minimum
Data of the effectiveness allow researchers to predict the clinical therapeutic index which is used to determine safe dosage.
Human testing occurs as final stage where patients are treated with the drug and researchers see if it suitable for humans.