PARASYMPATHOLYTICS

 

INTRODUCTION:  Drugs that block the action of Acetylcholine are known by a number of names, including anticholinergics, cholinergic blockers, muscarinic antagonists, and parasympatholytics.  Although the term anticholinergic is most commonly used, the most accurate term for this class of drugs is muscarinic antagonists, because at therapeutic doses, these drugs are selective for Ach muscarinic receptors and thus have little effect on Ach nicotinic receptors.

PHARMACODYNAMICS:  Anticholinergics act by competing with Ach for binding muscarinic receptors. When anticholinergics occupy these receptors, no response is generated at the neuroeffector organs. Suppressing the effects of Ach causes symptoms of sympathetic nervous system activation to predominate. Most therapeutic uses of the anticholinergics are predictable extensions of their parasympathetic-blocking actions: dilation of the pupils, increase in heart rate, drying of secretions, and relaxation of the bronchi.

THERAPEUTIC USES:  1. GI disorders:  These agents decrease the secretion of gastric acid in peptic ulcer disease. They also slow intestinal motility and may be useful for reducing the cramping and diarrhea associated with irritable bowel syndrome. 

2. Ophthalmic procedures:  Anticholinergics may be used to cause mydriasis or cycloplegia during eye procedures.

3. Cardiac rhythm abnormalities:  Anticholinergics can be used to accelerate the heart rate in patients experiencing bradycardia.

4. Preanesthesia:  Combined with other agents, anticholinergics can decrease excessive respiratory secretions and reverse the bradycardia caused by general anesthetics.

5. Asthma:  A few agents, such as ipratropium, are useful in treating asthma, because of their ability to dilate the bronchi.

6. Overactive bladder:  Anticholinergics treat urinary retention and incontinence.

7. Degenerative nervous system application:  Anticholinergics are used to treat patients who have Parkinson’s disease and whose main symptom is tremor. The prototype drug, atropine, is used for several additional medical conditions due to its effective muscarinic receptor blockade. These applications include reversal of adverse muscarinic effects and treatment of cholinergic agent poisoning, including that caused by overdose of bethanechol, cholinesterase inhibitors, or accidental ingestion of certain types of mushrooms or organophosphate pesticides.

 

RELATED;

1.  ACETYLCHOLINE

2.  CHOLINOMIMETICS

3.  GENERATION OF A NERVE IMPULSE

4.  DIVISIONS OF THE CENTRAL NERVOUS SYSTEM

5.  ATROPINE

REFERENCES

ALUMINUM HYDROXIDE

Therapeutic Class: Antiheartburn agent

Pharmacologic Class: Antacid

ACTIONS AND USES:  Aluminum hydroxide is an inorganic agent used alone or in combination with other antacids. Combining aluminum compounds with magnesium, increases their effectiveness and reduces the potential for constipation. Unlike calcium-based antacids that can be absorbed and cause systemic effects, aluminum compounds are minimally absorbed.  Their primary action is to neutralize stomach acid by raising the pH of the stomach contents.

Unlike H2-receptor antagonists and PPIs, aluminum antacids do not reduce the volume of acid secretion. They are most effectively used in combination with other antiulcer drugs for the symptomatic relief of heartburn due to PUD or GERD.

ADMINISTRATION ALERTS:  Administer aluminum antacids at least 2 hours before or after other drugs because absorption could be affected.  Pregnancy category C

ADVERSE EFFECTS: When taken regularly or in high doses, aluminum antacids cause constipation.

At high doses, aluminum products bind with phosphate in the GI tract and long-term use can result in phosphate depletion. Those at risk include those who are malnourished, alcoholics, and those with renal disease.

Contraindications: This drug should not be used in patients with suspected bowel obstruction.

INTERACTIONS:  Drug–Drug: Aluminum compounds should not be taken at the same time as

other medications, because they may interfere with absorption.

 

RELATED;

1.  PEPTIC ULCER DISEASE

2.  CONSTIPATION

3.  HISTAMINE 2 RECEPTOR BLOCKERS

4.  DIARRHEA

5.  PHARMACOLOGY AND THERAOEUTICS

REFERENCES

 

ATROPINE

 

Therapeutic Class: Antidote for anticholinesterase poisoning

Pharmacologic Class: Muscarinic cholinergic receptor blocker.

ACTIONS AND USES:  By occupying muscarinic receptors, atropine blocks the parasympathetic actions of Ach and induces symptoms of the fight-or-flight response. Most prominent are increased heart rate, bronchodilation, decreased motility in the GI tract, mydriasis, and decreased secretions from glands.  

At therapeutic doses, atropine has no effect on nicotinic receptors in ganglia or on skeletal muscle. Although atropine has been used for centuries for a variety of purposes, its use has declined in recent decades because of the development of safer and more effective medications. Atropine may be used to treat hypermotility diseases of the GI tract such as irritable bowel syndrome, to suppress secretions during surgical procedures, to increase the heart rate in patients with bradycardia, and to dilate the pupil during eye examinations. Once widely used to cause bronchodilation in patients with asthma, atropine is now rarely prescribed for this disorder. Atropine therapy is useful for the treatment of reflexive bradycardia in infants and infantile hypertrophic pyloric stenosis (IHPS).

 

ADMINISTRATION ALERTS

1.  Oral and subcutaneous doses are not interchangeable.

2. Monitor blood pressure, pulse, and respirations before administration and for at least 1 hour after subcutaneous administration.

3. Pregnancy category C.

 

ADVERSE EFFECTS:  The side effects of atropine limit its therapeutic usefulness and are predictable extensions of its autonomic actions. Expected side effects include dry mouth, constipation, urinary retention, and an increased heart rate. Initial CNS excitement may progress to delirium and even coma.

CONTRAINDICATIONS: Atropine is contraindicated in patients with glaucoma, because the drug may increase pressure within the eye. Atropine should not be administered to patients with obstructive disorders of the GI tract, paralytic ileus, bladder neck obstruction, benign prostatic hyperplasia, myasthenia gravis, cardiac insufficiency, or acute hemorrhage.

INTERACTIONS:  Drug–Drug: Drug interactions with atropine include an increased effect with antihistamines, TCAs, quinidine, and procainamide. Atropine decreases effects of levodopa.

TREATMENT OF OVERDOSE:  Overdose may cause CNS stimulation or depression. A short-acting barbiturate or diazepam (Valium) may be administered to control convulsions. Physostigmine is an antidote for atropine poisoning that quickly reverses the coma caused by large doses of atropine.

 

RELATED;

1.  ACETYLCHOLINE

2.  DIAZEPAM

3.  PHARMACOLOGY AND THERAPEUTICS

REFERENCES

 

 

OXYTOCIN

 

INTRODUCTION: Oxytocin stimulates contraction of the uterus at the end of pregnancy and stimulates release of milk from the mammary glands. As labor begins, the cervix of the uterus is stretched, which generates sensory impulses to the hypothalamus, which in turn stimulates the posterior pituitary to release oxytocin. Oxytocin then causes strong contractions of the smooth muscle also known as ,myometrium, of the uterus to bring about delivery of the baby and the placenta.

SECRETION OF OXYTOCIN: The secretion of oxytocin is one of the few positive feedback mechanisms within the body, and the external brake or shutoff of the feedback cycle is delivery of the baby and the placenta. It has been discovered that the placenta itself secretes oxytocin at the end of gestation and in an amount far higher than that from the posterior pituitary gland. Research is continuing to determine the exact mechanism and precise role of the placenta in labor.

When a baby is breast-fed, the sucking of the baby stimulates sensory impulses from the mother’s nipple to the hypothalamus. Nerve impulses from the hypothalamus to the posterior pituitary cause the release of oxytocin, which stimulates contraction of the smooth muscle cells around the mammary ducts. This release of milk is sometimes called the “milk let-down” reflex.

HUMAN LIFE AND THE ROLE OF PITUITARY GLAND: Both ADH and oxytocin are peptide hormones with similar structure, having nine amino acids each. And both have been found to influence aspects of behavior such as nurturing and trustfulness. Certain brain cells have receptors for vasopressin, and they seem to be involved in creating the bonds that sustain family life. Trust is part of many social encounters such as friendship, school, sports and games, and buying and selling, as well as family life. These two small hormones seem to have some influence on us mentally as well as physically.

RELATED;

1. FETAL DIAGNOSIS

2. STAGES OF LABOR

3. NORMAL LABOR AND VARGINAL DELIVERY

4.  PARTURITION AND LABOR

5.  PHARMACOLOGY AND THERAPEUTICS

REFERENCES

DIAZEPAM

 

Introduction:  Diazepine in trade names like Valium is one of the most commonly used Over The Counter (OTC) central nervous system agents 

Therapeutic Class: Antiseizure, Sedative-hypnotic drug 

Pharmacologic Class: Benzodiazepine; GABAA receptor agonist

ACTIONS AND USES: Diazepam binds to the GABA receptor–chloride channels throughout the CNS. It produces its effects by suppressing neuronal activity in the limbic system and subsequent impulses that might be transmitted to the reticular activating system. Effects of this drug are suppression of abnormal neuronal foci that may cause seizures, calming without strong sedation, and skeletal muscle relaxation. When used orally, maximum therapeutic effects may take from 1 to 2 weeks. Tolerance may develop after about 4 weeks. When given IV, effects occur in minutes, and its anticonvulsant effects last about 20 minutes.

ADMINISTRATION ALERTS: When administering IV, monitor respirations every 5 to 15 minutes. Have airway and resuscitative equipment accessible. The drug is pregnancy category D.

ADVERSE EFFECTS: Because of tolerance and dependency, use of diazepam is reserved for short term seizure control or for status epilepticus. When given IV, hypotension, muscular weakness, tachycardia, and respiratory depression are common.

Contraindications: When administered in injectable form, this medication should be avoided under the following conditions: shock, coma, depressed vital signs, obstetrical patients, and infants less than 30 days of age. In tablet form, the medication should not be administered to infants less than 6 months of age, to patients with acute narrow-angle glaucoma or untreated open-angle glaucoma, or within 14 days of monoamine oxidase inhibitor (MAOI) therapy.

INTERACTIONS: Drug–Drug: Diazepam should not be taken with alcohol or other CNS depressants because of combined sedation effects. Other drug interactions include cimetidine, oral contraceptives, valproic acid, and metoprolol, which potentiate diazepam’s action; and levodopa and barbiturates, which decrease diazepam’s action. Diazepam increases the levels of phenytoin in the bloodstream and may cause phenytoin toxicity.

RELATED;

1.  SEDATIV-HYPNOTICS  

2.  BENZODIAZEPINES

3.  DEPRESSION

4.  PHARMACOLOGY AND THERAPEUTICS

REFERENCES

IMIPRAMINE

 

Therapeutic Class: Antidepressant; treatment of nocturnal enuresis in children

Pharmacologic Class: Tricyclic antidepressant

ACTIONS AND USES: Imipramine blocks the re-uptake of serotonin and norepinephrine into nerve terminals. It is used mainly for major depression, although it is occasionally used for the treatment of nocturnal enuresis (bed wetting) in children. It may also be prescribed for a number of unlabeled uses, including intractable pain, anxiety disorders, and withdrawal syndromes from alcohol and cocaine. Therapeutic effectiveness may not occur for 2 or more weeks.

ADMINISTRATION ALERTS: Paradoxical diaphoresis can be a side effect of TCAs; therefore, diaphoresis may not be a reliable indicator of other disease states such as hypoglycemia.

Imipramine causes anticholinergic effects and may potentiate effects of anticholinergic drugs administered during surgery. Do not discontinue abruptly because rebound dysphoria, irritability, or sleeplessness may occur. Pregnancy category C.

ADVERSE EFFECTS: Side effects include sedation, drowsiness, blurred vision, dry mouth, and cardiovascular symptoms such as dysrhythmias, heart block, and extreme hypertension. Agents that mimic the action of norepinephrine or serotonin should be avoided because imipramine inhibits their metabolism and may produce toxicity. Some patients may experience photosensitivity and hypersensitivity to tricyclic drugs.

Warning: Antidepressants increase the risk of suicidal thinking and behavior, especially in children, adolescents, and young adults with major depressive disorder and other psychiatric disorders. This drug is not approved for use in pediatric patients. 

Contraindications: This drug should not be used in cases of acute recovery after MI, defects in bundle-branch conduction, narrow-angle glaucoma, and severe renal or hepatic impairment. Patients should not use this drug within 14 days of discontinuing MAOIs. 

INTERACTIONS: Drug–Drug: Concurrent use of other CNS depressants, including alcohol, may cause sedation. Cimetidine may inhibit the metabolism of imipramine, leading to increased serum levels and possible toxicity. Imipramine may reverse the antihypertensive effects of clonidine and potentiate CNS depression. Use of oral contraceptives may increase or decrease imipramine levels. Disulfiram may lead to delirium and tachycardia. Antithyroid agents may produce agranulocytosis. Phenothiazines cause increased anticholinergic and sedative effects. Sympathomimetics may result in cardiac toxicity. Methylphenidate or cimetidine may increase the effects of imipramine and cause toxicity. Phenytoin is less effective when taken with imipramine. MAOIs may result in neuroleptic malignant syndrome.

RELATED;

1.  DEPRESSION

2.  PHARMACOLOGY AND THERAPEUTICS

REFERENCES

MORPHINE

 

Therapeutic Class: Opioid analgesic

Pharmacologic Class: Opioid receptor agonist

ACTIONS AND USES: Morphine binds with both mu and kappa receptor sites to produce profound analgesia. It causes euphoria, constriction of the pupils, and stimulation of cardiac muscle. It is used for symptomatic relief of serious acute and chronic pain after non-narcotic analgesics have failed, as pre-anesthetic medication, to relieve shortness of breath associated with heart failure and pulmonary edema, and for acute chest pain connected with MI.

ADMINISTRATION ALERTS: The oral solution may be given sublingually. The oral solution comes in multiple strengths; carefully observe drug orders and labels before administering. Morphine causes peripheral vasodilation, which results in orthostatic hypotension. Pregnancy category B (D in long-term use or with high doses).

ADVERSE EFFECTS: Morphine may cause dysphoria (restlessness, depression, and anxiety), hallucinations, nausea, constipation, dizziness, and an itching sensation. Overdose may result in severe respiratory depression or cardiac arrest. Tolerance develops to the sedative, nausea-producing, and euphoric effects of the drug. Cross-tolerance also develops between morphine and other opioids such as heroin, methadone, and meperidine.

Physical and psychological dependence develops when high doses are taken for prolonged periods.

Warning: When morphine is administered as an epidural drug, due to the risk of adverse effects, patients must be observed in a fully equipped and staffed environment for at least 24 hours. Morphine administered as extended-release tablets has an abuse liability similar to other opioid analgesics. Morphine is a Schedule II controlled substance and should be taken properly according to dispensing instructions (i.e., tablets/capsules should be taken whole and not broken, chewed, dissolved, or crushed). Alcohol should be avoided with morphine products. Failure to follow these warnings could result in fatal respiratory depression.

Contraindications: Morphine may intensify or mask the pain of gallbladder disease, due to biliary tract spasms. Morphine should also be avoided in cases of acute or severe asthma, GI obstruction, and severe hepatic or renal impairment.

INTERACTIONS: Drug–Drug: Morphine interacts with several drugs. For example, concurrent use of CNS depressants, such as alcohol, other opioids, general anesthetics, sedatives, and antidepressants such as monoamine oxidase (MAO) inhibitors and tricyclics, potentiate the action of opiates, increasing the risk of severe respiratory depression and death.

RELATED;

1.  CHRONIC INFLAMMATION  

2.  OPIOID ANALGESICS

3.  PAIN AND IT'S MANAGEMENT

4.  PHARMACOLOGY AND THERAPEUTICS

REFERENCES

DRUG METABOLISM

Introduction:  Metabolism, also called biotransformation, is the process of chemically converting a drug to a form that is usually more easily removed from the body. Metabolism involves complex biochemical pathways and reactions that alter drugs, nutrients, vitamins, and minerals. The liver is the primary site of drug metabolism, although the kidneys and cells of the intestinal tract also have high metabolic rates. Medications undergo many types of biochemical reactions as they pass through the liver, including hydrolysis, oxidation, and reduction.

Microsomal enzyme systems:  During metabolism, the addition of side chains, known as conjugates, makes drugs more water soluble and more easily excreted by the kidneys. Most metabolism in the liver is accomplished by the hepatic microsomal enzyme system. This enzyme complex is sometimes called the P-450 system, named after cytochrome P-450 (CYP-450), which is a key component of the system. The cytochrome P450 enzyme system

Enzyme induction and the role of prodrugs:  As they relate to pharmacotherapy, the primary actions of the hepatic microsomal enzymes are to inactivate drugs and accelerate their excretion. In some cases, however, metabolism can produce a chemical alteration that makes the resulting molecule more active than the original. For example, the narcotic analgesic codeine undergoes biotransformation to morphine, which has significantly greater ability to relieve pain. In fact, some agents, known as prodrugs, have no pharmacologic activity unless they are first metabolized to their active form by the body. Examples of prodrugs include benazepril and, proinsulin and losartan. Changes in the function of the hepatic microsomal enzymes can significantly affect drug metabolism. A few drugs have the ability to increase metabolic activity in the liver, a process called enzyme induction. For example, phenobarbital causes the liver to synthesize more microsomal enzymes. By doing so, phenobarbital increases the rate of its own metabolism as well as that of other drugs metabolized in the liver. In these patients, higher doses of medication may be required to achieve the optimum therapeutic effect. 

Considerations for liver functioning states:  Certain patients have decreased hepatic metabolic activity, which may alter drug action. Hepatic enzyme activity is generally reduced in infants and elderly patients; therefore, pediatric and geriatric patients are more sensitive to drug therapy than middle-age patients. Patients with severe liver damage, such as that caused by cirrhosis, will require reductions in drug dosage because of the decreased metabolic activity. Certain genetic disorders have been recognized in which patients lack specific metabolic enzymes; drug dosages in these patients must be adjusted accordingly. Metabolism has a number of additional therapeutic consequences.  

The roles of fast-pass effect:  For example, drugs absorbed after oral administration cross directly into the hepatic portal circulation, which carries blood to the liver before it is distributed to other body tissues. Thus, as blood passes through the liver circulation, some drugs can be completely metabolized to an inactive form before they ever reach the general circulation. This first-pass effect is an important mechanism, since a large number of oral drugs are rendered inactive by hepatic metabolic reactions. Alternative routes of delivery that bypass the first-pass effect (e.g., sublingual, rectal, or parenteral routes) may need consideration for these drugs. 

RELATED;

1.  ABSORPTION  

2.  PHARMACOKINETICS

REFERENCES

DRUG ABSORPTION

 

Introduction: Absorption is a process involving the movement of a substance from its site of administration, across body membranes, to circulating fluids. Drugs may be absorbed across the skin and associated mucous membranes, or they may move across membranes that line the gastrointestinal (GI) or respiratory tract. Most drugs, with the exception of a few topical medications, intestinal anti-infectives, and some radiologic contrast agents, must be absorbed to produce an effect. Absorption is the primary pharmacokinetic factor determining the length of time it takes a drug to produce its effect. Pharmacokinetics

In order for a drug to be absorbed it must dissolve. The rate of dissolution determines how quickly the drug disintegrates and disperses into simpler forms; therefore, drug formulation is an important factor of bioavailability. Bioavailability

In general, the more rapid the dissolution, the faster the drug absorption and the faster the onset of drug action. For example, famotidine administered as an orally disintegrating tablet dissolves within seconds and after being swallowed is delivered to the stomach where it blocks acid secretion from the stomach, thereby treating conditions of excessive acid secretion. Pepticulcer disease: Histamine H2 receptor blockers

At the other extreme some drugs have shown good clinical response as slowly dissolving drugs such as liothyronine sodium (T3) and thyroxine (T4) administered for resolution of hypothyroid symptoms. In some instances it is advantageous for a drug to disperse rapidly. In other cases, it is better for the drug to be released slowly where the effects are more prolonged for positive therapeutic benefit. Absorption is conditional on many factors. Drugs in elixir or syrup formulations are absorbed faster than tablets or capsules. Drugs administered in high doses are generally absorbed more quickly and have a more rapid onset of action than those given in low concentrations. The speed of digestive motility, surface area, pH, lipid solubility, exposure to enzymes in the digestive tract, and blood flow to the site of drug administration also affect absorption. Because drugs administered IV directly enter the bloodstream, absorption to the tissues after the infusion is very rapid. IM medications take longer to absorb. Drug distribution

Other factors that influence the absorption of medications include the following: Drug formulation and dose, Size of the drug molecule, Surface area of the absorptive site, Digestive motility or blood flow, Lipid solubility, Degree of ionization, Acidity or alkalinity (pH), Interactions with food and other medications. The degree of ionization of a drug also affects its absorption. A drug’s ability to become ionized depends on the surrounding pH. Aspirin provides an excellent example of the effects of ionization on absorption. In the acid environment of the stomach, aspirin is in its non-ionized form and thus readily absorbed and distributed by the bloodstream. As aspirin enters the alkaline environment of the small intestine, however, it becomes ionized. In its ionized form, aspirin is not as likely to be absorbed and distributed to target cells.

Unlike acidic drugs, medications that are weakly basic are in their nonionized form in an alkaline environment; therefore, basic drugs are absorbed and distributed better in alkaline environments such as in the small intestine. The pH of the local environment directly influences drug absorption through its ability to ionize the drug.

Drug–drug or food–drug interactions may influence absorption. Many examples of these interactions have been discovered. For example, administering tetracyclines with food or drugs containing calcium, iron, or magnesium can significantly delay absorption of the antibiotic.  High-fat meals can slow stomach motility significantly and delay the absorption of oral medications taken with the meal. Dietary supplements may also affect absorption.

RELATED;

1.  DRUG DISTRIBUTION  

2.  PHARMACOKINETICS

3.  PHARMACOLOGY AND THERAPEUTICS

REFERENCES

ANTIBACTERIAL PROPERTIES OF GOLDENSEAL

 

INTRODUCTION:  Goldenseal (Hydrastis canadensis) was once a common plant found in woods in the eastern and midwestern United States. Native Americans used the root for a variety of medicinal applications, including skin diseases, ulcers, and gonorrhea. Recent uses include the treatment of colds and other respiratory tract infections, infectious diarrhea, eye infections, vaginitis, wounds, canker sores, and cancer.

Goldenseal was once reported to mask the appearance of drugs in the urine of patients wanting to hide drug abuse but this claim has since been proved false. The roots and leaves of goldenseal are dried and are available as capsules, tablets, salves, and tinctures. Two of the active ingredients in goldenseal are berberine and hydrastine, which are reported to have antibacterial properties.

When used topically or locally, goldenseal is claimed to be of value in treating bacterial and fungal skin infections and oral conditions such as gingivitis and thrush. As an eyewash, it can soothe inflamed eyes. Considered safe for most people, it is contraindicated in pregnancy and hypertension. Hypertension: Pregnancy and drug use

RELATED;

1.  GINSENG FOR CARDIOVASCULAR DISEASE  

2.  GARLIC FOR CARDIOVASCUAR DISEASE

REFERENCES

PHARMACOKINETICS

 

INTRODUCTION: The term pharmacokinetics is derived from the root words pharmaco, which means “medicine,” and kinetics, which means “movement or motion.” Pharmacokinetics is thus the study of drug movement throughout the body. In practical terms, it describes how the body deals with medications. Pharmacokinetics is a core subject in pharmacology, and a firm grasp of this topic allows the medical professionals to better understand and predict the actions and side effects of medications in patients. Drugs face numerous obstacles in reaching their target cells.  When we are addressing pharmacokinetic aspects of a drug, we shall be looking at its absorption from the site of injection or administration, distribution in the body tissues, metabolism and then it excretion from the body.

ABSORPTION OF DRUGS:  For most medications, the greatest barrier is crossing the many membranes that separate the drug from its target cells. A drug taken by mouth, for example, must cross the plasma membranes of the mucosal cells of the gastrointestinal tract and the capillary endothelial cells to enter the bloodstream. The plasma membrane

To leave the bloodstream, the drug must again cross capillary cells, travel through the interstitial fluid, and depending on the mechanism of action, the drug may also need to enter target cells and cellular organelles such as the nucleus, which are surrounded by additional membranes.  These are examples of just some of the barriers that a drug must successfully penetrate before it can produce a response. 

METABOLISM OF DRUGS:  While moving toward target cells and passing through the various membranes, drugs are subjected to numerous physiological processes. For medications given by the enteral route, stomach acid and digestive enzymes often act to break down the drug molecules. Enzymes in the liver and other organs may chemically change the drug molecule to make it less active.  If the drug is seen as foreign by the body, phagocytes may attempt to remove it, or an immune response may be triggered. 

DRUG EXCRETION:  The kidneys, large intestine, and other organs attempt to excrete the medication from the body. These examples illustrate pharmacokinetic processes: how the body handles medications. The many processes of pharmacokinetics are grouped into four categories: absorption, distribution, metabolism, and excretion as we have briefly seen here, and we shall be seeing in our next discussions in details.

RELATED;

1.  ROUTES OF DRUG ADMINISTRATION  

2.  BIOAVAILABILITY

3.  DYNAMICS OF DRUGS AND THE HUMAN BODY

4.  DRUG METABOLISM

5.  THE PLASMA MEMBRANE

6.  PHARMACOLOGY AND THERAPEUTICS

REFERENCES

PROCHLORPERAZINE

Therapeutic Class: Antiemetic

Pharmacologic Class: Phenothiazine antipsychotic

ACTIONS AND USES: Prochlorperazine is a phenothiazine, a class of drugs usually prescribed for psychoses. The phenothiazines are the largest group of drugs prescribed for severe nausea and vomiting, and prochlorperazine is the most frequently prescribed antiemetic in its class. Prochlorperazine acts by blocking dopamine receptors in the brain, which inhibits signals to the vomiting center in the medulla. Dopamine

As an antiemetic, it is frequently given by the rectal route, where absorption is rapid. It is also available in tablet, extended-release capsule, and IM formulations.

ADMINISTRATION ALERTS: Administer 2 hours before or after antacids and antidiarrheals. Pregnancy category C.

ADVERSE EFFECTS: Prochlorperazine produces dose-related anticholinergic side effects such as dry mouth, sedation, constipation, orthostatic hypotension, and tachycardia. When used for prolonged periods at higher doses, extrapyramidal symptoms resembling those of Parkinson's disease are a serious concern, especially in older patients.

Contraindications: This drug should not be used in patients with hypersensitivity to phenothiazines, in comatose patients, or in the presence of profound CNS depression. It is also contraindicated in children younger than age 2. Patients with narrow-angle glaucoma, bone marrow suppression, or severe hepatic or cardiac impairment should not take this drug.

INTERACTIONS: Drug-Drug: Prochlorperazine interacts with alcohol and other CNS depressants to cause additive sedation. Antacids and antidiarrheals inhibit the absorption of prochlorperazine. When taken with phenobarbital, metabolism of prochlorperazine is increased. Use with tricyclic antidepressants may produce increased anticholinergic and hypotensive effects.

RELATED;

1. NAUSEA AND VOMITING  

2. ENTERIC NERVOUS SYSTEM

3.  PHARMACOLOGY AND THERAPEUTICS

REFERENCES

METRONIDAZOLE (FLAGYL)

 

Introduction:  Metronidazole also sometimes referred to as fragyl, is one of the most commonly prescribed and used drugs because of availability, being cheap and broad spectrum of activity.  This drug can act against both bacteria, and protozoa.

Therapeutic Class: Anti-infective, antiprotozoan, and Antibacterial

Pharmacologic Class: Drug that disrupts nucleic acid synthesis and sometimes act as a proton sink, by depriving the microbe of oxidative potential.

Actions and uses: Metronidazole is the prototype drug for most forms of amebiasis, being effective against both the intestinal and hepatic stages of the disease. Resistant forms of E. histolytica have not yet emerged as a clinical problem with metronidazole therapy. Metronidazole is also a preferred drug for giardiasis and trichomoniasis. 

Metronidazole is unique among antiprotozoan drugs in that it also has antibiotic activity against anaerobic bacteria and thus is used to treat a number of respiratory, bone, skin, and CNS infections. 

Topical forms of metronidazole (MetroGel, MetroCream, MetroLotion) are used to treat rosacea, a disease characterized by skin reddening and hyperplasia of the sebaceous glands, particularly around the nose and face.

ADMINISTRATION ALERTS: The extended-release form must be swallowed whole and taken on an empty stomach. Metronidazole is contraindicated during the first trimester of pregnancy. Pregnancy category B

ADVERSE EFFECTS: Although adverse effects occur relatively frequently, most are not serious enough to cause discontinuation of therapy. The most common adverse effects of metronidazole are anorexia, nausea, diarrhea, dizziness, and headache. Dryness of the mouth and an unpleasant metallic taste may be experienced. Although rare, metronidazole can cause bone marrow suppression. 

Contraindications: Metronidazole is contraindicated in patients with trichomoniasis during the first trimester of pregnancy and those with hypersensitivity to the drug. Metronidazole can cause bone marrow suppression; thus, it is contraindicated for patients with blood dyscrasias.

INTERACTIONS: Drug–Drug: Metronidazole interacts with oral anticoagulants to potentiate hypoprothrombinemia. In combination with alcohol, or other medications that may contain alcohol, metronidazole may elicit a disulfiram reaction. In patients who are taking lithium, the drug may elevate lithium levels.

RELATED;

1.  FLOROQUINOLONES  

2.  PENICILLINS  

3.  CEPHALOSPORINS

4.  DRUG USE IN RELATION TO PREGNANCY

5.  PHARMACOLOGY AND THERAPEUTICS

REFERENCES

ECHINACEA FOR BOOSTING THE IMMUNE SYSTEM

 

Echinacea purpurea, or purple coneflower, is a popular botanical native to the midwestern United States and central Canada. The flowers, leaves, and stems of this plant are harvested and dried. Preparations include dried powder, tincture, fluid extracts, and teas. No single ingredient seems to be responsible for the herb’s activity; a large number of potentially active chemicals have been identified from the extracts. Echinacea was used by Native Americans to treat various wounds and injuries. Wound healing

Echinacea is believed to boost the immune system by increasing phagocytosis and inhibiting the bacterial enzyme hyaluronidase. Some substances in echinacea appear to have antiviral activity; thus, the herb is sometimes taken to treat the common cold and influenza, an indication for which it has received official approval in Germany. Clinical evidence for the effects of echinacea on upper respiratory tract infections is mixed, with some studies showing no effect and others showing a beneficial effect. In general, echinacea is used as a supportive treatment for any disease involving inflammation and to enhance the immune system. Inflammation: Immunity

Side effects are rare; however, it may interfere with drugs that have immunosuppressant effects.

RELATED;

1.  PASSIVE IMMUNITY  

2.  ACTIVE IMMUNISATION  

3.  SEA VEGETABLES

REFERENCES

GRAPE SEED EXTRACT FOR HYPERTENSION

 

Grapes and grape seeds have been to maintain and improve health used for thousands of years. Their primary use has been for cardiovascular conditions such as hypertension (HTN), high blood cholesterol, and atherosclerosis, and to generally improve circulation. Hypertension: Atherosclerosis

Some claim that grape seed extract improves wound healing, prevents cancer, slows the progression of neurodegenerative diseases, and lowers the risk for the long-term consequences of diabetes. Woundhealing: Diabetes

The grape seeds, usually obtained from winemaking, are crushed and placed into tablet, capsule, or liquid forms. Typical doses are 50 to 300 mg/ day. Grape seed extract has antioxidant properties that have the potential to improve wound healing and repair cellular injury. Grape seed extract is well tolerated in most people, with the most common side effects being dry, itchy scalp; dizziness; headache; hives; indigestion; and nausea. It has few adverse effects but caution should be used if taking anticoagulant drugs because increased bleeding may result.

RELATED;

1.  ARTERIOSCLEROSIS  

2.  GARLIC  

3.  BLOOD PRESSURE CONTROL

4.  TRADITIONAL AND COMPLIMENTARY MEDICATIONS

REFERENCES

HISTAMINE H2 RECEPTOR BLOCKERS

 

INTRODUCTION: Histamine has two types of receptors: H1 and H2. Activation of H1 receptors produces the classic symptoms of inflammation and allergy, whereas the H2 receptors are responsible for increasing acid secretion in the stomach. The H2-receptor antagonists are effective at suppressing the volume and acidity of parietal cell secretions. Duodenal ulcers usually heal in 6 to 8 weeks, and gastric ulcers may require up to 12 weeks of therapy. All of the H2-receptor antagonists are available OTC for the short-term (2 weeks) treatment of GERD.

Prototype Drug: Ranitidine

Therapeutic Class: Antiulcer drug

Pharmacologic Class: H2-receptor antagonist

ACTIONS AND USES: Ranitidine acts by blocking H2 receptors in the stomach to decrease acid production. It has a higher potency than cimetidine, which allows it to be administered once daily, usually at bedtime. Adequate healing of the ulcer takes approximately 4 to 8 weeks, although those at high risk for PUD may continue on drug maintenance for prolonged periods to prevent recurrence. Gastric ulcers require longer therapy for healing to occur. Intravenous (IV) and intramuscular (IM) forms are available for the treatment of acute, stress-induced bleeding ulcers. Ranitidine is available in a dissolving tablet form for treating GERD in children and infants older than 1 month of age. 

ADMINISTRATION ALERT: Administer after meals and monitor liver and renal function.

Pregnancy category B (Read about drug use in relation to pregnancy)

ADVERSE EFFECTS: Adverse effects are uncommon and mild. Ranitidine does not cross the blood–brain barrier to any appreciable extent, so it does not cause the confusion and

CNS depression observed with cimetidine. Although rare, severe reductions in the number of red and white blood cells and platelets are possible; thus, periodic blood counts may be performed. High doses may result in impotence or loss of libido in men.

Contraindications: Contraindications include hypersensitivity to H2-receptor antagonists, acute porphyria, and OTC administration in children less than 12years of age.

INTERACTIONS: Drug–Drug: Ranitidine has fewer drug–drug interactions than cimetidine. Ranitidine may reduce the absorption of cefpodoxime, ketoconazole, and itraconazole. Antacids should not be given within 1 hour of H2-receptor antagonists because the effectiveness may be decreased due to reduced absorption. Smoking decreases the effectiveness of ranitidine.

Lab Tests: Ranitidine may increase the values of serum creatinine, AST, ALT, LDH, alkaline phosphatase, and bilirubin. It may produce false positives for urine protein.

Herbal/Food: Absorption of vitamin B12 depends on an acidic environment; thus, deficiency may occur. Iron is also better absorbed in an acidic environment.

RELATED;

1. PROTON PUMP INHIBITORS  

2. ANTIBIOTICS  

3. PEPTIC ULCER DISEASE

4.  PHARMACOLOGY AND THERAPEUTICS

REFERENCES