Drug legislation and safety

In the United States, the Food and Drug Administration (FDA) is responsible for creating guidelines for the approval and use of drugs. The FDA requires that all approved drugs fulfill two requirements:

1. The drug must be found to be effective against the disease for which it is seeking approval.

2. The drug must meet safety criteria by being subject to extensive animal and controlled human testing.

Gaining FDA approval usually takes several years to attain. Testing done on animals must be extensive and must include several species to help in the evaluation of both the effectiveness and toxicity of the drug. The dosage of any drug approved for use is intended to fall within a range in which the drug produces a therapeutic effect or desired outcome.

The safety and effectiveness of prescription drugs in the U.S. is regulated by the Federal Prescription Drug Marketing Act of 1987.

The Medicines and Healthcare products Regulatory Agency (MHRA) has a similar role in the UK.

Education

The study of pharmacology is offered in many universities worldwide in programs that differ from pharmacy programs. Students of pharmacology are trained as researchers, studying the effects of substances in order to better understand the mechanisms which might lead to new drug discoveries for example. Whereas a pharmacy student will eventually work in a pharmacy dispensing medications or some other position focused on the patient, a pharmacologist will typically work within a laboratory setting.

PLACEBO

The placebo effect can be produced by inert tablets, by sham surgery, and by false information, such as when electrical stimulation is turned " off" in those with Parkinson's disease implanted brain electrodes.

A placebo is a sham medical intervention that produces a placebo effect. In medical research, placebos depend on the use of controlled and measured deception. Common placebos are inert tablets, sham surgery, and other procedures based on false information. In one common placebo procedure, a patient is given an inert pill, told that it may improve his/her condition, but not told that it is in fact inert. Such an intervention may cause the patient to believe the treatment will change his/her condition; and this belief may produce a subjective perception of a therapeutic effect, causing the patient to feel their condition has improved. This phenomenon is known as the placebo effect.

Placebos are widely used in medical research and medicine, and the placebo effect is a pervasive phenomenon; in fact, it is part of the response to any active medical intervention. When used as treatment in clinical medicine (as opposed to laboratory research), the deception involved in the use of placebos creates tension between the Hippocratic Oath and the honesty of the doctor-patient relationship. The House of Commons of the United Kingdom Science and Technology Committee states that: "...prescribing placebos... usually relies on some degree of patient deception" and " prescribing pure placebos is bad medicine. Their effect is unreliable and unpredictable and cannot form the sole basis of any treatment on the NHS."

Since the publication of Henry K. Beecher's “The Powerful Placebo” in 1955 the phenomenon has been considered to have clinically important effects. This view was notably challenged when in 2001 a systematic review of clinical trials concluded that there was no evidence of clinically important effects, except perhaps in the treatment of pain and continuous subjective outcomes. The article received a flurry of criticism, but the authors later published a Cochrane review with similar conclusions. Most studies have attributed the difference from baseline till the end of the trial to a placebo effect, but the reviewers examined studies which had both placebo and untreated groups in order to distinguish the placebo effect from the natural progression of the disease.

Definitions, effects, and ethics

A placebo has been defined as " a substance or procedure... that is objectively without specific activity for the condition being treated". Under this definition, a wide variety of things can be placebos and exhibit a placebo effect. Pharmacological substances administered through any means can act as placebos, including pills, creams, inhalants, and injections. Medical devices such as ultrasound can act as placebos. Sham surgery, sham electrodes implanted in the brain, and sham acupuncture, either with sham needles or on fake acupuncture points, have all exhibited placebo effects. Bedding not treated to reduce allergies has been used as a placebo to control for treated bedding. The physician has even been called a placebo; a study found that patient recovery can be increased by words that suggest the patient " would be better in a few days", and if the patient is given treatment, that " the treatment would certainly make him better" rather than negative words such as " I am not sure that the treatment I am going to give you will have an effect". The placebo effect may be a component of pharmacological therapies: pain killing and anxiety reducing drugs that are infused secretly without an individual's knowledge are less effective than when a patient knows they are receiving them. Likewise, the effects of stimulation from implanted electrodes in the brains of those with advanced Parkinson's disease are greater when they are aware they are receiving this stimulation. Sometimes administering or prescribing a placebo merges into fake medicine.

The placebo effect has sometimes been defined as a physiological effect caused by the placebo, but Moerman and Jonas have pointed out that this seems illogical, as a placebo is an inert substance which does not directly cause anything. Instead they introduced the word " meaning response" for the meaning the brain associates with the placebo, which causes a physiological placebo effect. They propose that the placebo, which may be unethical, could be avoided entirely if doctors comfort and encourage their patients' health. Ernst and Resch also attempted to distinguish between the " true" and " perceived" placebo effect, as they argued that some of the effects attributed to the placebo effect could be due to other factors.

The placebo effect has been controversial throughout history. Notable medical organizations have endorsed it, but in 1903 Richard Cabot concluded that it should be avoided because it is deceptive. Newman points out the " placebo paradox", - it may be unethical to use a placebo, but also unethical " not to use something that heals". He suggests to solve this dilemma by appropriating the meaning response in medicine, that is make use of the placebo effect, as long as the " one administering... is honest, open, and believes in its potential healing power."

PLACEBO IN HISTORY

The word placebo, Latin for “I shall please”, dates back to a Latin translation of the Bible by Jerome. It was first used in a medicinal context in the 18th century. In 1785 it was defined as a “commonplace method or medicine” and in 1811 it was defined as “any medicine adapted more to please than to benefit the patient”, sometimes with a derogatory implication but not with the implication of no effect. Placebos were widespread in medicine until the 20th century, and they were sometimes endorsed as necessary deceptions. In 1903 Richard Cabot said that he was brought up to use placebos, but he ultimately concluded by saying that “I have not yet found any case in which a lie does not do more harm than good”. In 1961 Henry K. Beecher found that patients of surgeons he categorized as enthusiasts relieved their patients' chest pain and heart problems more than skeptic surgeons. In 1961 Walter Kennedy introduced the word nocebo.

Mechanism of the effect

The phenomenon of an inert substance resulting in a patient's medical improvement is called the placebo effect. The phenomenon is related to the perception and expectation which the patient has; if the substance is viewed as helpful, it can heal, but if it is viewed as harmful, it can cause negative effects, which is known as the nocebo effect. The basic mechanisms of placebo effects have been investigated since 1978, when it was found that the opioid antagonist naloxone could block placebo painkillers, suggesting that endogenous opioids are involved.

Some unintended effects of chemicals found in cosmetics

Unfortunately, sometimes the ingredients in cosmetics can have unintended side-effects. For example, skin allergies (allergic dermatitis) to specific ingredients can be a problem. Allergies to cosmetic products can be due to chemicals such as added fragrances and preservatives. This can lead to a skin rash where the product is applied. If you think you may be allergic to a cosmetic product, it is important to determine which ingredients may be causing the problem. A specialised allergy test, called a patch test, may be helpful in this. Chemicals causing the allergy can then be avoided by reading product labels. Other people, while not allergic to a specific ingredient, may nevertheless find that a product irritates their skin because it damages the outer layers - a condition known as irritant dermatitis.

Exfoliates and skin peels leave the skin underneath temporarily more vulnerable to sun exposure because they remove the outermost protective layer of dead skin cells. Over-washing of hair or skin with soaps and detergents can strip the skin's natural protective oily layer, resulting in dry and scaly skin. Alternatively, excessive use of make-up or oily moisturisers can block pores and aggravate acne.

More serious side effects have been suggested for certain cosmetic ingredients. For example, a recent study was published that linked breast cancer with deodorants. The focus of the study was on parabens, a class of chemicals commonly used as preservatives in deodorants and antiperspirants. While parabens were found in breast cancer tissue, the study did not establish that they were the source of the cancer nor did it identify underarm cosmetics as the source of the chemicals.

A recent US study found that many cosmetics and toiletries used worldwide contained chemicals that were either known cancer-causing agents (carcinogens) or were untested for their effect on human health. More research into the safety of cosmetic chemicals is needed.

 

 

SOLUBILITY

Solubility is the property of a solid, liquid, or gaseous chemical substance called solute to dissolve in a solvent to form a homogeneous solution. The solubility of a substance fundamentally depends on the used solvent as well as on temperature and pressure.

The extent of the solubility of a substance in a specific solvent is measured as the saturation concentration where adding more solute does not increase the concentration of the solution.

Solubility occurs under dynamic equilibrium, which means that solubility results from the simultaneous and opposing processes of dissolution and phase joining.

The solubility equilibrium occurs when the two processes proceed at a constant rate.

The term solubility is also used in some fields where the solute is altered by solvolysis. For example, many metals and their oxides are said to be " soluble in hydrochloric acid, " whereas the aqueous acid degrades the solid to give soluble products.

It is also true that most ionic solids are degraded by polar solvents, but such processes are reversible. In those cases where the solute is not recovered upon evaporation of the solvent, the process is referred to as solvolysis. The thermodynamic concept of solubility does not apply straightforwardly to solvolysis.

In general, solubility in the solvent phase can be given only for a specific solute that is thermodynamically stable, and the value of the solubility will include all the species in the solution.

A popular aphorism used for predicting solubility is " like dissolves like". This statement indicates that a solute will dissolve best in a solvent that has a similar chemical structure to itself. This view is simplistic, but it is a useful rule of thumb. The overall solvation capacity of a solvent depends primarily on its polarity.

For example, a very polar (hydrophilic) solute such as urea is very soluble in highly polar water, less soluble in fairly polar methanol, and practically insoluble in non-polar solvents such as benzene. In contrast, a non-polar or lipophilic solute such as naphthalene is insoluble in water, fairly soluble in methanol, and highly soluble in non-polar benzene.

The solubility of one substance in another is determined by the balance of intermolecular forces between the solvent and solute, and the entropy change that accompanies the solvation. Factors such as temperature and pressure will alter this balance, thus changing the solubility.

The solubility of a given solute in a given solvent typically depends on temperature. For many solids dissolved in liquid water, the solubility increases with temperature up to 100 °C.

Solubility is of fundamental importance in a large number of practical applications, ranging from ore processing, to the use of medicines. Solubility is often said to be one of the ‘characteristic properties of a substance’.

The synthesis of chemical compounds, by the milligram in a laboratory, or by the ton in industry, both make use of the relative solubilities of the product, as well as starting materials, and side products to achieve separation.

SOLUTION

 

In chemistry, a solution is a homogeneous mixture composed of only one phase, In such a mixture, a solute is a substance dissolved in another substance, known as a solvent. The solvent does the dissolving. The solution more or less takes on the characteristics of the solvent including its phase, and the solvent is commonly the major fraction of the mixture. The concentration of a solute in a solution is a measure of how much of that solute is dissolved in the solvent. 

Types of solutions

Homogeneous means that the components of the mixture form a single phase. The properties of the mixture (such as concentration, temperature, and density) can be uniformly distributed through the volume but only in absence of diffusion phenomena or after their completion. Usually the substance present in the greatest amount is considered the solvent. Solvents can be gases, liquids, or solids. One or more components present in the solution other than the solvent are called solutes: The solution has the same physical state as the solvent.

Gas

If the solvent is a gas, only gases are dissolved under a given set of conditions. An example of a gaseous solution is air (oxygen and other gases dissolved in nitrogen). Since interactions between molecules play almost no role, dilute gases form rather trivial solutions. In part of the literature, they are not even classified as solutions, but addressed as mixtures.

Liquid

If the solvent is a liquid, then gases, liquids, and solids can be dissolved. Here are some examples:

 

1. Gas in liquid:

· Oxygen in water.

· Carbon dioxide in water is a less simple example, because the solution is accompanied by a chemical reaction (formation of ions). Note also that the visible bubbles in carbonated water are not the dissolved gas, but only an effervescence of carbon dioxide that has come out of solution; the dissolved gas itself is not visible since it is dissolved on a molecular level.

 

2. Liquid in liquid:

· The mixing of two or more substances of the same chemistry but different concentrations to form a constant.(Homogenization of solutions)

· Alcoholic beverages are basically solutions of ethanol in water.

 

3. Solid in liquid:

· Sucrose (table sugar) in water

· Sodium chloride or any other salt in water forms an electrolyte: when dissolving, salt dissociates into ions.

Counter examples are provided by liquid mixtures that are not homogeneous: colloids, suspensions, emulsions are not considered solutions.

Body fluids are examples for complex liquid solutions, containing many different solutes. They are electrolytes since they contain solute ions such as potassium. Furthermore, they contain solute molecules like sugar and urea. Oxygen and carbon dioxide are also essential components of blood chemistry, where significant changes in their concentrations may be a sign of illness or injury.

Solid

If the solvent is a solid, then gases, liquids, and solids can be dissolved.

1. Gas in solid:

• Hydrogen dissolves rather well in metals, especially in palladium; this is studied as means of hydrogen storage.

2. Liquid in solid:

• mercury in gold, forming an amalgam

• hexane in paraffin wax

3. Solid in solid:

• steel, basically a solution of carbon atoms in a crystalline matrix of iron atoms.

• alloys like bronze and many others.

• polymers containing plasticizers.

Properties

The physical properties of compounds such as melting point and boiling point change when other compounds are added. Together they are called colligative properties. There are several ways to quantify the amount of one compound dissolved in the other compounds collectively called concentration. Examples include molarity, mole fraction, and parts per million (PPM).

The properties of ideal solutions can be calculated by the linear combination of the properties of its components. If both solute and solvent exist in equal quantities (such as in a 50% ethanol, 50% water solution), the concepts of " solute" and " solvent" become less relevant, but the substance that is more often used as a solvent is normally designated as the solvent (in this example, water).

 

 

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