Site hosted by Angelfire.com: Build your free website today!

 

For Your Information

 

 

  1. Body membranes that affect drug distribution.

  1. Cell membranes

  2. Capillaries

  3. Blood-Brain Barrier

  4. Placental Barrier

    1. Placental membranes are unique in that they separate two individual beings with different genetic compositions, physiological responses, and sensitivities to drugs.

    2. The fetus obtains essential nutrients and eliminates metabolic waste products through the placenta without depending on its own organs, many of which are not yet functioning.

    1. This dependence of the fetus upon the mother, however, places the fetus at the mercy of the placenta when foreign substances (such as drugs or toxins) appear in the mother's blood.

    1. Pregnant women in the United States regularly take both prescription and nonprescription drugs, and they routinely expose the fetus to potentially toxic substances in foods, cosmetics, household chemicals, and the general environment.

    1. The extent to which these substances affect the fetus is not yet known.

    2. The consequences of maternal alcohol ingestion, cigarette smoking, and cocaine use on fetal growth and development are now well documented.

    1. The view that the placenta is a barrier to drugs is inaccurate! A more appropriate approximation is that the fetus is to at least some extent exposed to essentially all drugs taken by the mother.

    2. The mother's blood (and all the substances that it contains) is transferred to the fetus within the Placental Barrier and returns from the fetus to the mother in the same manner for cleansing in the liver and kidneys. During the fetal stages, the fetus's liver and kidneys do not function and many times this lasts for a time after birth.

    1. There are specific drug-metabolizing enzymes in the liver of the mother. Unfortunately, the newborn (especially the premature infant) has few of these drug-metabolizing enzymes in its liver, and its kidneys may not yet be fully functional.

    2. Therefore, the infant has difficulty metabolizing and excreting drugs. If it has received a high concentration of depressants (anesthetics, narcotics, and so on) from the mother, the infant may be depressed for a long time after delivery. The same holds true for stimulants (nicotine, caffeine, narcotics and so on) which have been introduced into the mother's blood causing post-natal withdrawal symptoms, agitation, sleeplessness and anxiety in the newborn infant.

    3. There is a growing amount of concern over the transfer of psychoactive drugs (such as nicotine) from mothers to their breast-fed babies. Another area of growing concern has been expressed about the secretion of antibiotics that have been administered to cows into milk that is ultimately consumed by humans.

  1. Caffeine (a psychoactive drug and stimulant).

  1. Caffeine content in beverages, foods, and medicines. Recommended daily dose not to exceed 50-75 mg/day.

ITEM Average (mg) Range (mg)

(Anacin, Midol, Vanquish)……………………………..33

    1. Pharmacokinetics of caffeine.

      1. Significant blood levels of caffeine are reached in 30 to 45 minutes and complete absorption within the nest 90 minutes, with levels in plasma peaking in about 2 hours.

      2. The half-life of caffeine is about 3.5 to 5 hours in most adults; it is longer in infants, pregnant women, and the elderly and shorter in smokers.

      3. Like all psychoactive drugs, caffeine freely crosses the placenta to the fetus.

      1. Caffeine has a longer half-life in the human fetus than in the adult because the fetus does not have the liver enzymes for detoxifying caffeine. The half-life of caffeine in the pregnant woman increases from 3 to 10 hours by the latter part of pregnancy.

      2. Concentrations of caffeine in breast milk equal or may even exceed the level that exists in the mother's plasma. In an infant this can cause wakefulness, restlessness, agitation, anxiety, tremors, rapid breathing, and insomnia.

      1. Journal of the American Medical Association (1993) reports:

      1. Caffeine was relatively safe in moderate doses (less than 300 milligrams per day or less than 3 medium sized cups of coffee per day). At higher levels, an increased incidence of intrauterine growth retardation was seen.

      2. A second report in the same magazine states: Low doses of caffeine (about 160 mg/day) in the first trimester of pregnancy increased the risk of intrauterine growth retardation; high consumption (greater than 300 mg/day), even in the month before pregnancy, "nearly doubled the risk of spontaneous abortion." *

    * I just have a sub-note to add to all this…Even though most doctors don't consider caffeine as being detrimental during pregnancy, the truth is they will readily admit to the fact that there is no conclusive evidence pointing toward caffeine not having any bad effects on fetal growth and development along with early spontaneous abortion. In other words, they can't say for sure it won't affect the fetus. Most young people only consider their caffeine intake as how much coffee they consume. They tend not to consider the tea, chocolate, pop and medications they also consume. You must also consider that the 1/2 life of caffeine (how long it takes for 1/2 of the amount of intake to leave the body) is about 30 minutes. This means if you drink one cup of coffee (about 75 mg of caffeine) it will take 30 minutes to lose 1/2 the caffeine (37.5 mg). Then you drink another cup of coffee. Now you have a half-life of 37.5 (for the new cup) and 18.7 (for the first cup). If you repeat this every half-hour for 3 hours, you will reach a terminal intake point of 75 mg and it will remain constant. If your initial consumption is greater than a small cup (75 mg) or if it is more often than every half hour, these ratios increase proportionately. So, you can see how easy it can be, in a day, to reach a lethal dose level of caffeine for a fetus or an unhealthy dose for a breast fed baby seeing as how mother’s milk has concentrated doses of caffeine with higher levels than what is carried in the mother’s blood.

    1. Nicotine (a psychoactive drug and depressant/stimulant).

    1. Nicotine and the other ingredients in tobacco are responsible for a wide variety of health problems, including the deaths of more than 1,100 Americans every day!

      1. Each day 3,000 children become regular smokers, and almost 1,000 of them will eventually die from diseases related to smoking (think of it…1 in 3 will die!!). Also, 9 in 10 smokers become addicted before age 21. If you smoke, your children are much more likely to smoke. Smoking during pregnancy and breast feeding as well as second hand smoke in juveniles will increase the chances of becoming a smoker significantly.

      2. On the positive side, half of all persons who have ever smoked cigarettes have quit, and the proportion of American adults who smoke has fallen from 50 percent in 1965 to 26 percent in 1995. As stated by the Surgeon General, "Smoking will continue as the leading cause of preventable, premature death for many years to come."

      3. It is also important to realize that, in our further discussions in this outline, nicotine is only one of about 4,000 compounds released by the burning of cigarette tobacco. Nicotine accounts only for the acute pharmacological effects of smoking and for the dependence on cigarettes. The adverse, long-term cardiovascular, pulmonary, and carcinogenic effects of cigarettes are related to other compounds contained in the product.

    1. Pharmacokinetics (The process by which a drug is absorbed, distributed, metabolized and eliminated by the body).

      1. Nicotine is easily absorbed into the blood stream from almost any sight on the body or in it. This easy and complete absorption forms the basis for the recreational abuse of smoked or chewed tobacco, as well s the medical use of nicotine (in treating nicotine dependency) in gums, nasal sprays, transdermal skin patches, and smokeless inhalers.

      2. Nicotine is suspended in cigarette smoke in the form of minute particles (tars), and it is quickly absorbed into the bloodstream from the lungs when the smoke is inhaled.

      1. The toxicity within the body is easily and very accurately controlled by the number of breathes taken, the amount of smoke inhaled, the time smoke is held in the lungs, and the number of cigarettes smoked. Chewing tobacco offers the same safe levels of toxicity dosage.

      1. Nicotine is quickly and thoroughly distributed throughout the body, rapidly penetrating the brain, crossing the placental barrier, and appearing in all the bodily fluids, including breast milk. The elimination half-life of nicotine in a chronic smoker is about two hours, necessitating frequent administration of the drug to avoid withdrawal symptoms or drug craving.

    1. Pharmacological Effects (what nicotine does).

      1. In the early stages of nicotine use, there is accompanying nausea and vomiting since it stimulates both the vomiting center in the brain stem and the sensory receptors in the stomach. A rapid tolerance for this effect develops with continued use.

      2. Nicotine stimulates the hypothalamus to release a hormone, antidiuretic hormone (ADH), which causes fluid retention.

      3. Nicotine use leads to a reduction in muscle tone.

      4. Nicotine can induce tremors (the shakes) and, in toxic overdose, seizures.

      5. As with all stimulant drugs, there is period of depression following use. This may explain the urgent need to have a smoke first thing in the morning.

      6. Recent papers have reported antidepressant effects of nicotine as well as the comorbidity (connection) of childhood attention deficit hyperactivity disorder (ADHD) and depression with cigarette use and of adult depressive disorders and nicotine dependence.

      1. There was a study that showed that non-smokers who had depression when given a nicotine patch experienced relief from the depression. It was also found that the vast majority of depressed persons smoke. Therefore, cigarette smoking may be an attempt at self-medication for symptoms of depression.

      1. Without getting real technical (some of the words are million dollar suckers), I will try to explain how nicotine affects the heart. First off, nicotine increases heart rate, blood pressure, and cardiac contractility (heart contractions). This causes the arteries leading to the heart to dilate (expand) in an attempt to get more oxygen to the heart muscle. However, the veins leaving the heart cannot dilate to accommodate the influx of blood. This can precipitate angina (painful heart contractions) or myocardial infarction (a heart attack).

    1. Tolerance and Dependence.

      1. I am not going to go into great detail here. You know how addictive cigarettes are already. I just want you to know they have compared the addiction to nicotine to the addictions to drugs such as heroin and cocaine. This is because they seem to affect the same areas of the brain and trigger the same reinforcing methods.

    1. Toxicity.

      1. The toxic substances in cigarette smoke are nicotine, carbon monoxide, and tars. Of the more than 435,000 persons in the U.S. who die annually from tobacco use, 82,000 deaths are caused by non-cancerous lung diseases, 112,000 are caused by lung cancer, 30,000 are caused by cancers of other body organs, and more than 200,000 result from heart and vascular diseases.

      2. A person's life is shortened 14 minutes for every cigarette smoked ( 2 packs/day for 20 years = a loss of 8 years of life).

      3. More than 50 million people (one out of every five Americans) will die prematurely from the effects of smoking cigarettes. Globally, tobacco is responsible for about 2.5 million deaths per year.

    1. Cardiovascular Disease.

      1. Carbon monoxide decreases the amount of oxygen delivered to the heart muscle, while nicotine increases the amount of work that the heart must do (by increasing the heart rate and blood pressure). Both carbon monoxide and nicotine increase the incidence of atherosclerosis (narrowing) and thrombosis (clotting) in the coronary arteries (this is what I was saying earlier in 3 - g). These three actions, along with others, seem to underlie the fivefold to nineteen-fold increase in the risk of death from coronary heart disease in smokers as compared to nonsmokers. If the smoker has pre-existing hypertension or diabetes, the risk is magnified.

    1. Cancer.

      1. SUFFICE TO SAY THAT CIGARETTE SMOKING CAUSES CANCER WITHOUT A DOUBT!!!

      1. In the lungs, the cancer used to attack the upper trunks until they introduced reduced tar and nicotine filters. Now the cancer attacks the smaller, outer branches of the lungs. Both types are fatal.

      2. Smoking is also the major cause of cancers of the mouth, voice box, and throat. The use of alcohol along with smoking increases the incidence of these problems.

      3. Smoking is a primary cause of more than 50% of the nearly 10,000 deaths every year that result from bladder cancer, it is a primary cause of pancreatic cancer, and it increases the risk of cancer of the uterine cervix twofold.

    1. Effects of Passive (second hand) Smoke.

      1. It has been determined that nonsmokers exposed to passive smoking have a coronary death rate 20 to 70 percent higher than nonsmokers not exposed to passive smoking.

    1. Effects During Pregnancy.

      1. Smoking causes increased rates of spontaneous abortion, stillbirth, and early postpartum (shortly after birth) death. More than 2,000 infant deaths per year are attributed to maternal smoking. There is also evidence that infants born of smoking mothers may be growth retarded as compared to those born of nonsmoking mothers.

      2. Cigarette smoking reduces oxygen delivery to the developing fetus, causing fetal hypoxia (a deficiency of oxygen reaching developing tissues), which can result in long-term, irreversible intellectual and physical deficiencies.

      3. There is also evidence that school-age children born of mothers who smoked during pregnancy have lower intelligence quotients (IQ) and an increased prevalence of ADHD when compared with children born of nonsmoking mothers.