Drugs and medicine hub

Drugs are used to prevent,diagnose and treat diseases.Drugs (therapeutic drugs or medicines) are any substances exogenous or endogenous e.g (synthetic drugs,hormones,antibiotics,peptides,DNA fragments etc.)that elevate or lower body's function according to their own nature,when introduced into the body by interacting with a specific molecule or receptor in the body.

Drugs don't provide new function to organism despite they increase or decrease the existing physiological or biochemical functions in the body.Although every tissue has some ability to metabolise drugs,however liver is the principle organ of drug metabolism.Liver has cytochrome P450 enzyme that's the main source of drug metabolism.

Drugs need to cross various biological membranes with lipid properties to arrive at the action site to produce corresponding effects after entering the body.This transmembrane transport of drugs canbe chiefly divided into two patterns: (1)Passive transport & (2)Carrier-mediated transport. The majority of drugs are transported in the body by passive transport in which drugs are transported from a region of higher concentration to lower concentration without the need of energy. Passive transport maybe further classified into simple diffusion and filtration.Carrier-mediated transport of drugs include actiive transport of drugs and facilitated diffusion. Transmembrane movement of drugs in th body with active transport doesn't depend on the concentration gradient across the membrane but the process needs special carriers and energy.For instance,the drugs are excreted from the renal tubules by active transport.Facilitated diffusion occurs with the help of special carriers present inside the membrane and requires no energy but drugs are not capable of transportng accross the concentration gradient e.g glucose and amino acids are transported by facilitated diffusion.

It's necessary for the health care providers to be familiar with the factors that affect drug's effectiveness in order to optimize and minimize the adverse effects of medication.These factors may lie with the individual or the drug itself.The best example to comprehend this is to consider patients of different ages receiving different doses and under some circumstances different drugs due to different pharmacokinetic and pharmacodynamic features of drugs. Phrmacokinetics is simply a process of absorption,distribution,metabolism and excretion of drugs in the body while pharmacodynamics address biochemical and biophysical actions of drugs on the body, the mechanism of their action and the dose-effect relatonship of drugs.

Individual factors: like age,gender,body weight ,genetic factors,timing of medication,psychological and pathological factors play an important role in the therapeutic outcome of drugs.

Drugs factors: Include factors like physical nature of a drug & its route of adminstration,drug-drug interactions and long term use of drugs,all have an important role in determining the success or failure of therapy.

Age:Generally child doses and elderly doses are kept lower than adult doses because of low drug hepatic metabolism and renal excretion than those of young to middle aged adults.Child doses are given to patients under 14 years of age.Adult doses are used for the group between 14 and 60.Elderly doses are for the people over 60.Proper dose is the amount that produces desired effects and minimal adverse reactions.

Gender:Basically there are no apparent differences as people of both genders react to drugs similarly.However,some special periods of women shouldbe considered in the process of medication e.g In menstruation, drugs affecting uterus contraction shouldbe avoided to prevent over bleeding.In pregnancy,extreme care shouldbe taken for the safety of both mother and fetus.And during lactation,attention shouldbe paid to some drugs that excrete via milk.

 Drugs used on proper timings affects remarkably drug therapy.Therefore,its always beneficial not to use the drugs before or after the time advised by a physician.Its because of the biological rhythms in the human body that affect the outcome of drugs.

Circadian rhythm of body is a good example where the secretion of cortex hormones is featured by day-night rhythm that's caused by adrenocorticoid secretion.The corticoid level in the plasma reaches a peak in the early morning and a trough in the midnight.If exogenous glucocorticoids are used at the peak time of their natural secretion in the body by adrenal gland,it minimises the drug induced adrenocortical insufficiency which is an adverse effect of glucocorticoids.

Adrenocorticotropic hormone(ACTH) is secreted by anterior pituitary gland under the control of another hormone, Corticotrophin release hormone (CRH) secreted by hypothalmus.ACTH maintains the normal form and function of adrenal gland.Glucocorticoids produced by adrenal cortex have a negative feed back effect on hypothalmus and anterior pituitary gland to suppress the secretion of CRH and ACTH.In a physiological condition, hypothalamus,pituitary and adrenal gland are in a dynamic steady state.If there is lack of ACTH,adrenal cortex will atrophy and the secretory function will decrease.

Concurrent adminstration of medicines and nutrients can lead to interactions that change their absorption,distribution or metabolism. Some of these interactions have little or no impact on the patient while others maybe harmful or even fatal.So simultaneous use of more than two drugs shouldbe based on their pharmacokinetic and pharmacodynamic features of a druge.g Warfarin has a high protein binding rate resulting in competitive binding of other drugs like Phenylbutazone.If phenylbutazone is adminstered concurrently with warfarin,it increases the bleeding danger.

Some disease require long term use of medication that may cause some reaction to drugs.Here are they:

Tolerance:As a consequence of continual drug adminstration the intensity of drug response to a given dose may change during the course of therapy.Many drugs may develop tolerance such as the opiods and CNS depressants. Dependance:Its usually assocuiated with drug abuse in which a person may get addicted becoming psychologically or physiologically dependant. Withdrawal syndrome:Sudden withdrawal of some drugs after long tern use results in withdrawal symptoms e.g adrenocorticoids abrupt termination causes symptoms such as fatigue & depressed mood.Its advisable not to abruptly stop using a therapeutic drug after a long term use.