Coffee has been the most commercialized food product and most widely consumed beverage in the world. Most (more than 80%) of the world’s population consume coffee. It is a major source of caffeine, which is the most widely used stimulant. Caffeine (1,3,7-trimethyl xanthine), the natural alkaloid, is the well-known component of coffee. Both the United States Department of Agriculture (USDA) and the European Food Safety Authority (EFSA) consider a daily intake of 400 mg of caffeine as safe. Eventhough this amount is safe for health; it causes different clinically significant pharmacokinetical interactions with some drugs. In addition to caffeine, coffee also contains other components which are responsible to pharmacokinetic interaction with different medications. This paper reviews the research findings and clinical case studies on the effect of coffee on pharmacokinetic behavior of drugs. Several studies evidently show that coffee affects the pharmacokinetic behavior of some drugs. The aim of this work was to review the effect of coffee on the absorption, distribution and elimination of some drugs by investigating invitro and invivo pharmacokinetic studies and clinical case reports.
Coffee
Coffee is a popular drink as people throughout the world are starting and finishing their days with cups of coffee. It is a major source of caffeine which is the most widely consumed stimulant in the world. About 80 % of the world’s population consumes coffee and other coffee product each day, and this number goes up to 90 % for adults in North America. Coffee has been the most commercialized food product and most widely consumed beverage. In 2015, coffee production reached more than 8.1 million tons worldwide per year. This represents more than 500 billion cups .
The coffee tree belongs to the Rubiaceae family, genus Coffea. Although more than 80 coffee species have been identified worldwide, only two are economically important. Coffea arabica, also known as Arabica coffee, is responsible for approximately 70 % of the global coffee market, and Coffea canephora or Robusta coffee (commercial name of one of the main C. canephora cultivars) accounts for the rest. Coffee started its journey at least 1200 years ago in Ethiopia, then followed by Yemeni Sufi monasteries in the Middle East and northern Africa, Europe, America and so on .
Green coffee is composed primarily of caffeine, water, carbohydrates and fiber, proteins and free amino acids, lipids, minerals, organic acids, chlorogenic acids, trigonelline and other compounds as shown in Table 1. From these compounds found in green coffee chlorogenic acids, caffeine, Trigonelline and diterpenes are most likely to be bioactive, and they may also be important contributors to the beverage flavor after roasting.
Caffeine is a methylxanthine with bitter characteristics; however, it is responsible for no more than 10 % of the perceived bitterness of the coffee beverage. It stimulates the central nervous system (CNS) as an adenosine-receptor antagonist. Trigonelline is also one of the constituents of coffee biologically derived from enzymatic methylation of nicotinic acid. It contributes to the bitterness as well as the precursor for the formation of different classes of volatile compounds during roasting. On the other hand, chlorogenic acids confer astringency, bitterness, and acidity to the coffee brew. Carbohydrates are also the major constituents of coffee and may account for more than 50 % of the dry weight. Sucrose is another important component for coffee flavor and quality; it accounts for up to 9 %.
Caffeine (1, 3, 7-trimethyl xanthine) is the natural alkaloid and the most known bioactive component of coffee. Caffeine structure is shown in Figure 1. It is the most bioactive component of coffee. This psychoactive ingredient was isolated in 1820 from the coffee beans and now being used in a number of food and drinks.
The amount of caffeine present in a cup of coffee varies between 83 and 179 mg. Both the US Department of Agriculture (USDA) and the European Food Safety Authority (EFSA) consider a daily intake of 400 mg of caffeine as safe. This amount is approximately from 2–3 cups of coffee per day. Eventhough this amount is considered safe for health; it causes different clinically significant pharmacokinetical interactions with many drugs. Excessive caffeine intake is especially prevalent in psychiatric patients as they are frequently exposed to depression. About 22 % of psychiatric inpatients using more than 750 mg/day compared with 9% of the general population.
Pharmacokinetics
Pharmacokinetics is the study of “what the body does to a drug”. It focus on ADME which refers to four processes relevant to pharmacokinetics, with A standing for absorption (how the drug gets into the body), D for distribution (where the drug goes once inside the body), M for metabolism (what enzymes metabolize what drugs, and how rapidly drugs are metabolized) and E for excretion (how drugs are removed from the body) . Pharmacokinetics is more accurately described by the acronym “ITE”. In this case, I stands for input into the body as some routes of administration do not have absorption step (such as intravenous administration), T for transfer of drug within the body and finally E for elimination from the body (which includes metabolism since metabolism is a major route of drug elimination).
The biological, physiological and physicochemical factors which influence the movement of drugs in the body influence the rate and extent of ADME of those drugs in the body. There are different factors which affect the pharmacokinetics of drugs by the different mechanism such as by altering the absorption, distribution and excretion. Induction or inhibition of metabolizing enzymes is also another mechanism to affect the pharmacokinetics of drugs. Drug interaction studies fall into three broad categories: drug – drug interactions, drug – food/beverage interactions and drug – condition interactions. One of the factors which affect pharmacokinetic of drugs is food and beverages. Coffee is one of the most known beverages which have pharmacokinetic interaction with many drugs.
Patients as well as healthy people throughout the world are starting and finishing their days with cups of coffee. Eventhough coffee has numerous benefits to our body, there are also clinically significant pharmacokinetic interaction between coffee and many important over-the-counter as well as prescription medications due to its major constituents mainly caffeine and Chlorogenic acid. The aim of this work was to review the effect of coffee on the absorption, distribution and elimination of some drugs.
THE EFFECT OF COFFEE ON ABSORPTION OF DRUGS
Absorption is the movement of a drug from its site of administration into the central compartment and the extent to which this occurs. For solid dosage forms, absorption first requires dissolution step to liberate the drug. The common disadvantage of the oral route is limited absorption of some drugs because of their physical characteristics (e.g., low water solubility or poor membrane permeability), emesis as a result of irritation to the GI mucosa, destruction of some drugs by digestive enzymes or low gastric pH, irregularities in absorption or propulsion in the presence of foods and beverages (eg. coffee) or other drugs, and the need for co-operation on the part of the patient .
Coffee can affect the absorption process of drugs by changing dissolution profile, destroying drugs by changing GI pH, by affecting sink condition of GI membrane and blood, by affecting GI emptying time, by formation of complex, and so on.
