Microbial Loads In Herbal Medicines

Medicines are substances in which when taken into the body takes particular pathways and causes biological changes to the benefit of animals and humans. Pharmacokinetics is the term used to describe routes medicines use when taken into the body. These include; Absorbtion, Distribution, Metabolism, and Excretion (ADME). Medicines taken orally (through the mouth) are absorbed after administration ( solid forms are first broken down to increase surface area for absorbtion) from the digestive system. The portal vein (a type of blood vessel) then carry the absorbed principles to the liver before it reaches the rest of the body. The liver then reduces the concentration of these medicines such that only a small amount is available for transport throughout the body by the circulatory system to their site of action and thus maximum response to medicine reduces. This effect by the liver is called the first pass effect.

Different routes of drug administration are thus preferred aside the oral route to maximize response especially in emergencies and certain disease conditions. These include : rectal, vaginal, intravenous, intramuscular, and other routes. The effect of medicines is very high with these routes as there is direct entry into the body’s circulatory system and increased drug availability at the diseased site. Pharmacodynamics on the other hand is the term used to describe the study of the biochemical and physiological effects of medicines on the body and the mechanisms of drug action. Both pharmacokinetics and pharmacodynamics help explain the relationship between the dose and response of medicines or drugs i.e drug’s effects on the body.

Safety and efficacy are the two main factors considered in the production of medicines particularly herbal medicines for human consumption. Herbal medicines are usually prepared by grinding or steeping the parts of a plant or plants that are believed to contain medicinal properties. The ground plant matter is called the “macerate.” The macerate is soaked in a liquid referred to as the “menstruum” in order to extract the active ingredients. Herbal infusions are prepared by treating the herb with water or alcohol (ethanol) or mixtures of the two; coarsely bruised drug boiled in water for a definite period is known as a decoction and tinctures are solutions of the active principles of the drug in alcohol and water. This extraction process leads to the production of the herbal preparations in the form of fresh juice, hot and cold infusions, decoctions, tinctures, pastes, and powders referred to as “pulverata.” These serve as basis for finished herbal products such as capsules, bitters, ointments, creams, soaps, shower gels, syrups, etc. Solid or powdered extracts are prepared by evaporation of the solvents used in the process of extraction of the raw material.

To ensure the safety of herbal medicines especially finished products, the preparation aside good manufacturing procedure should be subjected to some studies: toxicity, microbial load determination, phytochemical screenings, physicochemical analysis among others. Physicochemical test helps determine the _PH of manufactured products. Increased _PH suggests that a product is less acidic and safe for consumption and also unconducive for microbial growth. It is carried out with the aid of a pH meter and pH paper.

Medicines (except sterile preparations) both orthodox or herbal have permissible range of microorganism as directed by standard reference books in their production. However preparations such as eye drops, ear drops, intravenous preparations etc have no microorganisms and are thus referred to as Sterile preparations or products. The permissible range for microorganisms in orthodox medicines is far reduced as compared to herbal medicines due to factors such as the nature of starting materials, conditions of production, etc.

Microbial load determination is carried out in a microbiology facility or laboratory as described in reference book such as the British Pharmacopoeia (BP), (2009). Here the product is applied on different media available for cultivating particular microorganisms and the Medias incubated at a particular temperature for a particular duration. For instance in determining the microbial load of a formulated anti-malarial herbal product (decoction), two sterilized petri dishes are employed for each different media in the experiment as control and test experiment and each set of petri dish is labeled. 1ml of the preparation is then serially diluted three times using 1 in 10 dilution i.e 1ml of product in 9ml of distilled water in first test tube, 1ml of mixture of first test tube in 9 ml distilled water for second test tube, 1ml of mixture from second test tube in 9ml distilled water for third test tube to inactivate the preservative in the product. 1 ml of the diluted preparation in the third test tube is then added to each petri dish labelled for test experiment. Different agar medium is liquefied by placement in a heated water bath and 20ml of each poured into the respective petri dishes and allowed to set. The petri dishes are the incubated at 37^o C for 72 hours. The number of growth or colony-forming units on each plate is counted and recorded. The herbal product is said to have passed the test if the number of colonies counted falls within the reference or permissible range and does not contain infectious microorganisms thus is safe for human consumption.

Microbial load determination is among the series of tests conducted on medicinal products by the Food and Drugs Authority as they serve as standards for registration. Consumers are therefore advice to only buy FDA approved herbal medicines and avoid buying unregistered products in vehicles, market places, etc.

BENTIL EMMANUEL ASARE
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