Thursday, June 18, 2009

Management of Hyperlipidemia

Elevated levels of fatty components in our blood is termed as hyperlipidemia. It is considered as a primary risk factor for coronary heart disease (CHD), stroke and peripheral vascular disease irrespective of the gender of a patient. Hyperlipidemia may complicate the health status in association with the diabetes, hypertension and kidney disease. There exists a strong association between the total cholesterol level and CHD. The cholesterol homeostasis is maintained by the liver and small intestine through very delicate balance of cholesterol input (dietary intake and de-novo synthesis of cholesterol) and elimination by conversion to bile and through fecal excretion. In the liver cells (hepatocytes) low density lipoprotein cholesterol (LDL-C) is produced through the conversion of HMG-Coenzyme-A (HMG-CoA) to mevalonic acid. It is important to note that LDL-C is a bad lipid whereas HDL-C is good. There is need to keep a check on the level of cholesterol in general and LDL-C in particular.

Cardiovascular morbidity and mortality is directly associated with the level of total cholesterol and LDL-C, and inversely with the level of high density lipoprotein cholesterol HDL-C). Cholesterol-enriched and triglyceride-rich lipoproteins, including very low density lipoproteins (VLDL) and intermediate density lipoproteins ((IDL) could also promote atherosclerosis. The elevated level of LDL-C warrants the need of cholesterol lowering therapy, inclusive of life style modification and cholesterol lowering drugs. HMG-CoA reductase inhibitor or statins are the most potent and widely used drugs for treating hypercholesterolemia or hyperlipidemia because of their efficacy in reducing LDL-C to the desired level as recommended by the National Cholesterol Education Program (NCEP). For effective control of hyperlipidemia around 20-55% reduction in the level of LDL-C needs to be achieved by Statins. The hyperlipidemia may be primary (heterozygous familial or non-familial hyperlipidemia) or secondary to some other disorder like renal disease. It has been established now that ezetimibe as monotherapy in association with customized diet, effectively reduces the elevated level of total cholesterol, LDL-C, Apo-B and triglycerides, and increases the level of HDL-C in patients with hypercholesterolemia. Ezetimibe is a selective cholesterol absorption inhibitor and was approved by FDA about 8 years ago. Statins (atorvastatin, lovastatin, pravastatin and simvastatin) are potent, HMG-CoA reductase inhibitors. The combination of ezetimibe and atorvastatin or simvastatin is effective therapy for taming down the elevated levels of total cholesterol and LDL-C in patients with homozygous familial hypercholesterolemia (HoFH). The treatment of hyperlipidemia should be commenced under medical advice and follow-up with biochemical evaluation of lipids in blood.

Important tip: Kill the fat before it kills you.

Saturday, June 13, 2009

Post Exposure Prophylaxis Therapy for HIV

The impact of exposure to human immunodeficiency virus (HIV) depends on two main factors: (1) Nature of exposure and (2) The status of the source patient (the patient to whose blood or body fluids exposure has occurred). There is need to evaluate the source patient within 2 hours of exposure so that post exposure prophylaxis (PEP) could be started. The initiation of PEP should not be delayed more than 72 hours in any case. The baseline HIV testing should also be done for the exposed person before starting post exposure prophylaxis therapy. The post exposure prophylaxis refers to the comprehensive management given to the exposed person to minimize the risk of infection following potential exposure to blood-borne viruses (HIV, HBV and HCV). The risk assessment could only be evaluated through relevant laboratory investigations. Antiretroviral therapy should be started after consultation with the physician and follow up and supportive counseling should be provided to the exposed person at the surveillance centers.


The relative risk of HIV transmission after different routes of exposure has been established as under:


Exposure Route

HIV Transmission

Blood transfusion90-95%
Sexual intercourse-Vaginal1-10%
Sexual intercourse-anal0.05-0.5%
Sexual intercourse-oral0.005-0.01%
Perinatal20-40%
Intravenous drug use0.5-1%
Needle stick injury0.5%
Mucous membrane splash to eyes0.1%

The exposure to blood, semen, vaginal secretions, cerebrospinal fluid, synovial fluid, pleural fluid, pericardial fluid and amniotic fluid is considered risky and infectious. However, exposure to tears, sweat, urine, faeces and saliva is not considered infectious unless these secretions contain blood. The exposure is considered mild if the contact is with the eyes or mucous membranes or there is needle stick injury with small bore needle generally during vaccination or skin testing. The exposure is considered moderate if the mucous membranes or intact skin is exposed to large volume of body fluid or blood of the infected patient. A cut with surgical blade or needle stick injury with blood smeared needle. The exposure is considered severe if the accidental prick is with high bore (> 18G) needle contaminated with blood or a deep wound is caused with surgical knife smeared with blood. Transfusion of infected blood or packed cells.


The prescription of post exposure prophylaxis depends on the category of exposure. For mild exposure, basic regimen or 2-drug combination is generally prescribed depending on the status of the source of exposure. If the exposure source is HIV+ but asymptomatic, consider 2-drug PEP and if the source is HIV+ and clinically symptomatic, immediately start 2-drug PEP. In case of moderate exposure to HIV+ but asymptomatic source, start 2-drug PEP. If the source is found HIV+ and clinically symptomatic in case of moderate exposure, start expanded regimen which is 3-drug combination. In case of severe exposure to an HIV+ but asymptomatic or clinically symptomatic source, immediately start 3-drug combination. PEP regimens prescribed by health centers are: (1) 2-drug regimen: Zidovudine (AZT) + Lamivudine (3TC) or Stavudine (d4T) + Lamivudine (3TC). (2) 3-drug regimen: Zidovudine (AZT) + Stavudine (d4T) + Lamivudine (3TC). Expert opinion is must before starting PEP therapy.

Friday, June 12, 2009

Antimicrobial Agents and Drug Resistant Bacteria

There are about a dozen antimicrobial agents (AMA) and an equal number of bacterial types or species which are resistant to one or the other afore said antimicrobial agent or antibiotic. A list of these antimicrobial agents or antibiotics and corresponding resistant bacteria has been cited in the table-1 below. Antimicrobial susceptibility testing (AMST) against these antimicrobial agents or antibiotics with reference to corresponding bacteria could be discontinued to save time and money.


Table-1: Antimicrobial agents or antibiotics and resistant bacteria


Antimicrobial agentResistant Bacteria
AminoglycosidesAnaerobic bacteria, Enterococci and Streptococci
AmpicillinKlebsiella species
AztreonamGram-positive bacteria
VancomycinGram-negative bacteria
Sulphonamides, trimethoprimProteus aeruginosa
Tetracycline, chloramphenicolP. aeruginosa
All cephalosporinsEnterococci
AminoglycosidesEnterococci
ImipenemStenotrophomonas maltophilia
MetronidazoleAerobic bacteria