Thursday, March 31, 2011

Imipramine

It is an anti-arrhythmic drug and belongs to class IA of drugs.

Action:
It inhibits the reuptake of serotonin and norepinephrine.

Uses:
It is an anti-arrhythmic drugs and is also used in depression and enuresis in children aged 6 years.

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Tuesday, March 29, 2011

Worldwide Cancer Status

Cancer is found to be the leading cause of death in the world with the 13% of all death cases around the world in 2008. About 12.7 million cases of cancer and 7.6 million deaths were calculated in 2008. Upto middle-income countries there are about half (51%) of all cancer cases worldwide in 1975; while this proportion increased to 55% in 2007 and is thought to reach 61% by the year 2050.
There are more than 100 types of cancer and it can affect any part of the body.

Two factors are increasing the number of worldwide cancer patients:
1. Aging
2. Cancer causing attitude such as use of tobacco (It is estimated that about 1.3 billion people worldwide smoke tobacco), harmful or damaging use of alcohol, physical inactivity or poor diet
3. Older age
4. Race
5. Family history

Apart from these factors some other factors can also cause cancer such as
1. Over weight and obesity (WHO estimates that in 2005, overweight adults were about 1.6 billion from the total population and 300 million obese. It is estimated that the number of overweight people may go upto 2.3 billion by the year 2015.
2. Exposure to environmental carcinogens such as radon, arsenic, asbestos and polycyclic aromatic hydrocarbons.
3. Chronic Infections

A large number of cancer cases and deaths are in developing countries.More than 70 % of all cancer deaths occured in developing countries.
Breast Cancer is leading type of cancer in females and lung cancer is the leading type of cancer in males, since 1985, and they are also the leading cause of death from cancer for both developing as well as developed world. In females, lung cancer is the fourth most commonly diagnosed cancer and second most important cause of death from cancer. According to 2003-2007 research, top 5 cancer sites are prostate (a gland males that surround the tube for discharging urine located below the bladder), Breast, Lung as well as Bronchus and Colon (part of large intestine) as well as rectum (lower part of the large intestine).

Incidence rates of cancer is twice as high in developed countries as compared to developing countries.

It has been estimated that more than 30% of cancer deaths can be prevented by preventing the use of tobacco, taking a healthy diet, showing physical activity, and by prevention of infections that may cause cancer such as chronic (old) infections of hepatitis B virus (HBV) and/or human papillomavirus (HPV).

References:
Jemal, A.; Bray, F.; Center, M. M.; Ferlay, J.; Ward, E.; Forman, D. 2011.
Global cancer statistics. A Cancer Journal for Clinicians, 61, Pages 69-90.

SEER Cancer Statistics Review 1975-2007. 2007. http://seer.cancer.gov/csr/1975_2007/browse_csr.php?section=1&page=sect_01_table.23.html#b . Accessed Mar 30, 2011.

Thun, M. J.; DeLancey, J. O. et al. 2010. The global burden of cancer: priorities for prevention. Carcinogenesis, Volume 31, Issue 1, Pages 100-110.
World Health Organization (WHO), Cancer; Fact Sheet. Feb 2011,  http://www.who.int/mediacentre/factsheets/fs297/en/ . Accessed Mar 30, 2011.

Nitroglycerin

It is also referred to as “Glyceryl trinitrate”.


Mechanism of action:
Intracellularly, Nitroglycerin gives nitrite ions, which then changes into endothelium derived relaxing factor (EDRF) i.e. nitric oxide. This NO then reacts with sulfhydryl (-SH) containing receptors associated with guanylate cyclase resulting in the activation of soluble Guanylate cyclase which promotes cells’ cyclic GMP level, which activates protein kinase G leading to the dephosphorylation of the myosin light chain. This causes ion binding process of Ca2+and at last relaxation of the vascular smooth muscle.

Actions:

It causes a reduced cardiac work resulting in the decreased oxygen demand of the heart muscles.

1. It causes venodilation so that blood is pooled in the veins resulting in the decreased preload and work of the heart.
2. It causes an increased flow of blood to the myocardium by dilating the coronary vessels.

Pharmacokinetics:
Its onset of action is one minute. It undergoes through the first pass metabolism and that is why it is taken sublingually or via transdermal patches.

Therapeutic uses:
Sublingual nitroglycerin is used for immediate relief from angina induced by physical activity or stress.

Nitrites and nitrates

These are nitric and nitrous acid esters of glycerol.

Mechanism of action:
1. Nitrates cause relaxation of the coronary vessels resulting in the decreased constriction of coronary vessels. The decreased constriction of the coronary arteries leads to increased transfusion of blood to the muscles of the heart (improved letting of blood).

2. On the other hand, it promotes dilation of the capacitance veins resulting in the decreased venous return to the heart due to pooled effect of blood in the veins. This decreased venous return to the heart decreases oxygen demand of the muscles of the heart.


Actions:

CVS:
Relaxation occurs in all segments of vascular system:
1. Less dilation of the arterioles and precapillary sphincters due to reflex responses.
2. They reduces cardiac output.
3. It effects directly on coronary artery tone resisting coronary artery spasm in variant angina.


4. Organonitrates causes relaxation of the arteries resulting in the reduced systemic arterial pressure causing reduced afterload of the heart leading to the reduced cardiac oxygen requirement.

5. Organonitrates causes relaxation of the veins resulting in the reduced preload causing reduced myocardial wall tension leading to reduced myocardial oxygen requirement.
6. Reduced left ventricular end diastolic volume reduces tissue pressure around subendocardial vessels  promoted coronary blood flow to this area

Other smooth muscle organs:
Organonitrates have short duration of action on the relaxation of the smooth muscles i.e. esophageal and biliary smooth muscle.

Blood:
Nitrite ion may cause pseudocyanosis and tissue hypoxia.
Therapeutic uses:
1. Stable and unstable angina pectoris
2. Variant angina pectoris
3. Orthopnea and Paroxysmal nocturnal dyspnea
4. Cyanide poisoning

Adverse effects:
Facial flushing (due to cutaneous vasodilation), Severe type of headache (due to vasodilation of cerebral vessels leading to elevated intracranial pressure and headache), Orthostatic hypotension, dizziness, weakness

Nadolol

This has a long duration of action.


Therapeutic uses:
1. Hypertension
2. Angina pectoris
3. Cardiac tachyarrhythmias

Implants

This represents the form of radiation therapy or radiotherapy involving placement of radioactive entities inside the body of the patient close to the tumor.

An artificial body part placed in tissues (often to replace missing body parts) with the help of surgery.