DRUG SPECTRUM OF ACTIVITY

DRUG SPECTRUM OF ACTIVITY:  Today we have thousands of different types of drugs i different formulations treating different diseases.  But the question would be; Which drug is best in treating disease X?  And the immediate answer will be, there are several drugs that all can cure the same disease, X.  And then the next question will be; How do I choose from drug A, B, C, and D the best and affordable drug for myself and or the patient?  Then the answer will be; Before you think about affordability, look at the spectrum of activity for each specific drug and then choose accordingly.  In our discussion here, we are going to look at how specific drugs will be able to treat specific infections with maximum efficiency but before we continue, if you have not been following us, you may also be interested in reading about; Dynamics of drugs and the human body and Classification of drugs

When it comes to drug actions especially antimicrobial agents or dugs that kill microbes, there is a range of organisms onto which the drug will be effective.  Some drugs are capable of killing a wide range of microbes while others can just kill a few or even one strain of microbes.  In our discussion here, we are going to look at the range of microbes that can be killed by specific drugs but before we continue, if you have not been following us, you may want to read about classification of drugs that we discussed recently from the link below;  Classification od drugs

BROAD SPECTRUM ANTIBIOTICS:  As we continue looking at antimicrobial agents, we have drugs that can target several microbes and therefore such drugs can be given in multiples infections with various microbes.  These are collectively known as broad spectrum antibiotics.  If these are antibacterial let's say, they will be able to handle both gram positives and gram negative bacteria or even having a potential to tackle on acid fast bacilli too.  And we we have several classes of drugs here as we are going to be briefly mentioning a couple of them.

Previously we have been looking at the different types antibiotics basing on their mechanism of action and in some of our previous discussions we looked at classification of drugs basing on the microbes they act upon.  Some of the examples of broad spectrum antibiotics we can have here are specific to bacteria and they include but not limited to; 1) Metronidazole, a nitroimidazole that can be used to treat both bacteria and protozoa.

NARROW SPECTRUM ANTIBIOTICS:  So much we have seen when it comes to broad spectrum antibiotics, now let us look drugs with a narrow spectrum of activity.  These are drugs that are limited in action and they will be able to kill just a selected number of microbes.  In this set of drugs, we look at drugs like Isoniazid, which is almost entirely active on only mycobacteria.

RELATED;

1.  CLASSIFICATION OF DRUGS

2.  DYNAMICS OF DRUGS AND THE HUMAN BODY

3.  METRONIDAZOLE

4.  ISONIAZID

CONCURRENT USE OF OVER THE COUNTER (OTC) DRUGS

CONCURRENT USE OF OVER THE COUNTER (OTC) DRUGS:  In drug use, we have two broad categories namely; Over the counter drugs (OTC) and Prescription only Medications (POM).  The first category looks at drugs and medications that clients can easily buy from drug shops and any type of retail shop without official consultation from a trained and authorized medical personnel.  The last one, describes those drugs that can only be given and only allowed to be given following a medical prescription and directions from a trained medical personnel.  The medical prescription.  Whether a pharmaceutical product bought from a recognised pharmacy, a traditional medication from traditional healers and drug shops selling traditional and complimentary medications or drugs of abuse such as alcohol and caffeinated drinks, the brief pharmacological intervention of all chemicals bought relieve some sort of disorder qualifies to be OTC.  In our discussion here, we are going to look at the OTC drugs and their types, and then the consequences of their use in humans.

COMMON OTC DRUGS:  Some of the most common drugs used as the "Over the Counter medications" include but not limited to analgesics or literally known as pain killers.  These drugs are bought and used by clients after having extraneous activities, following toothache and for others, after sensation of fever. Here we have some common drugs including but not limited to; Paracetamol (Panadol), Indomethacin (Indocid), Diclofenac and Ibuprufen among others.  We also commonly have clients buy antibiotics of different types and among some of the most common include but not limited to; Metronidazole, Amoxicillin, Artemisinin combination Therapies and others.  There is also misuse of peptic ulcer medications such as Omeprazole and antiacids containing magnesium and aluminum and antihistamine.

Such drugs have ever been prescribed to the patient and or, they have been used by the patient for a long period of time.  The so called pain killers are used by many people in our communities day to day.  These are the likes of Indomethacin, Dicrofenac, Paracetamol or Acetaminophene among others.  But the use of these drugs comes at a cost, that they are not the safest chemical to use frequently.

Despite the fact that they may not be the perfect medications to be used for whatever condition the patient may be using them for, there is no thorough evaluation of the patients' condition before their use, and they are normally used in either under or overdose for Un predetermined time.

CONSEQUENCES OF USING OTC:  Some of the most common consequences of using on the counter drugs comes as a result of ether underdose and or overdose, irrational prescription, or drug resistance.  Let us look at each drug manufactured and marketed to have a predetermined dosage regimen where, you are required to take some amount of the drug in  a given time t.  Sometimes you notice that depending on the patient's status, the dosage can be adjusted at various degrees making let's say a drug being available in 20mg, 40mg and 45 mg per Kg body weight.  It will not be easy for a non medical personnel buying such a drug to notice the different strength, subjecting them to less or more than the actual dose they need.  I have discussed a lot about therapeutic window and therapeutic index in the past as you can read about the details from here.

When it comes to irrational prescription, there is a tendency of patients to buy drugs that because their presenting signs and symptom are similar to those that a friend had, and they saw the drug they were given.  When it comes to Drug resistance, this is one of the major topics of concern when it come to antimicrobial drug use especially the so called antibiotics.  Without a proper laboratory investigation and consultation from a trained medical personnel, there would be no need to take any antibiotic for any anticipated medical condition.

RELATED;

1.  DYNAMICS OF DRUGS AND THE HUMAN BODY

2.  DRUG USE AND CLINICAL TRIALS

3.  DRUG USE IN RELATION TO PREGNANCY

4.  CLASSIFICATION OF DRUGS

5.  ANALGESICS

6.  ANTIBIOTICS

ALCOHOL AND THE HUMAN BODY

Introduction:  In our day to day life we tend to take in many stuff in our bodies some of which are helpful and others are harmful.  Whether intentional or accidentally taken, every chemical that we consume in our bodies has limits with in which it will be either useful or harmful and today, let us look at the comings and goings of alcohol in the human body and the effects both short term and long term of it's consumption.

Ethyl alcohol or simply alcohol has few clinical uses when given systemically, but is of great medical importance because of its pathological and psychological effects when used as a beverage in beers, wines, vodkas and other local and international alcoholic beverages.  Seasonal consumers of alcohol have some benefit from it and these are some of the few here; It is a sedative but not a perfect sedative-hypnotic.  I have discussed much about sedation and hypnosis and if you would like to read more about Sedative-hypnotics click here.  Alcohol in small quantities is capable of causing depressant states but it is not a perfect depressant.  So for that respect, many people tend to take it when they feel hyperactive to gain some feeling of depression especially following extraneous activities that require mental hassling.  Following ingestion of alcohol, there may be some feeling of pain killing or relief in some painful situations but it is not a perfect analgesic or what people literally call "pain killer" and it is never in any way intended for that purpose.  

Alcohol is one of the most important drug of dependence and abuse, and in many countries, the incidence of alcoholism is about 10% among the adult population.

Pharmacokinetics:  Ethyl alcohol is absorbed from the buccal, oesophageal, gastric and intestinal mucosae, and approximately 80% is absorbed from the small intestines.  In fact this makes it one of the most easily absorbable compounds when taken orally, and one of the drugs that can achieve maximum bioavailability in a short period of time.  I have discussed about the term bioavailability in relation to drug absorption and distribution recently and if you would like to read about that, you can click here. 

Alcohol delays gastric emptying and in high doses delays its own absorption. Following oral administration, alcohol can usually be detected in the blood within five minutes.  Alcohol is capable of crossing the placenta and the fetus can be exposed to it following drinking for pregnant mothers.  The effects of alcohol is so intense in pregnancy that when a mother drinks, the fetus will have almost the same concentration of alcohol in it's blood as that of the mother's blood per in mg/dl.  This is indicative of the degree with which it crosses the placenta compared to other compounds, and an alert on the possible initiation and development of teratogens or fetal malformations.

Peak concentrations occur between 30 minutes and two hours and during this period, the quantity taken and the amount reaching the body systems will be following a first order kinetics fashion. It should be noted that, Fats and carbohydrates delay absorption and therefore may affect. Alcohol is distributed throughout the body water. About 95% is metabolized mainly in the liver and the remainder is excreted unchanged in the breath, urine and sweat.

Effects of alcohol:  Alcohol has several effects on the different body systems as follows;

Nervous system: Alcohol decreases concentration, judgement, discrimination, and reasoning and increases self-confidence. Progressively increasing plasma concentrations are associated with sensations of relaxation followed by mild euphoria, incoordination, ataxia and loss of consciousness. 

At high blood concentrations, the gag reflex is impaired, vomiting may occur and death may result from aspiration of gastric contents. The importance of alcohol as a factor in road traffic accidents is well known. 

The central depressant actions of alcohol greatly enhance the effects of other central depressant drugs. In patients with organic brain damage, alcohol may induce unusual aggression and destructiveness, known as pathological intoxication.

Medical uses of alcohol:  Alcohol may seem to be a universal poison because of it's hazardous effects on the human body when consumed in large quantities and for a long time however, there times when it can be used as a medicine.  Alcohol is used topically as an antiseptic and many antiseptic solutions have some alcoholic component in them. In fact the smell of alcohol can be detected by exposed individual on use of sanitizing solutions.  Systemic alcohol is used in poisoning by methanol or ethylene glycol, since it competes with these for oxidation by alcohol dehydrogenase, slowing the production of toxic metabolites such as formaldehyde, oxalic acid.  We shall late be discussing the toxicities that result form alcohols including methanol in a separate discussion.

Conclusion:  Health experts say that is good to have some sort of alcoholic beverage in a day with a daily recommendation of 2 bottles of bear for men and 1 bottle for women.  The recommendation however may be different depending on the region and someone's health status.  Small quantities of alcohol are shown to increase the efficiency and normal functioning of the cardiovascular system and Gastrointestinal tract.  The problem however comes that once taken, alcohol tends to make an individual develop tolerance and dependance to it.  Increasing intake of large quantities of alcohol is associated with Nervous system, Cardiovascular and GIT related medical conditions as seen above. 

RELATED;

1.  ADDICTION, TOLERANCE AND DEPENDENCY

2.  ALCOHOL BREAKDOWN BY THE LIVER

3.  FUNCTIONS OF THE LIVER

4.  ALCOHOL LIVER FAILURE

5.  ALTERED LEVEL OF CONSCIOUSNESS

6.  SEDATIVES AND HYPNOTICS

7.  CENTRALLY ACTING DRUGS

8.  BIOAVAILABILITY

REFERENCES

THERAPEUTIC INDEX AND THERAPEUTIC WINDOW

 

INTRODUCTION:  Administering a dose of the drug that produces an optimum therapeutic response for each individual patient is only one component of effective pharmacotherapy. Medical practitioners must also be able to predict whether the dose is safe for the patient and this is one other thing that is fully tested during clinical trials.  Frequency distribution curves can also be used to represent the safety of a drug. For example, the median lethal dose (LD₅₀) is often determined in preclinical trials, as part of the drug development process. The LD₅₀ is the dose of drug that will be lethal in 50% of the investigation group of animals. As with ED₅₀, a group of animals will exhibit considerable variability in lethal dose; what may be a nontoxic dose for one animal may be lethal for another.

DETERMINATION OF THERAPEUTIC INDEX:  To examine the safety of a particular drug, the LD₅₀ can be compared with the ED_50. For example, 10 mg of drug X is the average effective dose, and 40 mg is the average lethal dose. The ED₅₀ and LD₅₀ can then be used to calculate an important value in pharmacology, a drug’s therapeutic index, which is the ratio of a drug’s LD₅₀ to its ED₅₀.  

THERAPEUTIC WINDOWS:  Now that we have looked at therapeutic index as a ration, therapeutic window on the other side, is a range between the drug that can cause a desired effect in 50% also known as Effective dose 50 (ED50) of the investigational animals to the drug dose that can cause toxicity in 50% of the investigational animals also known as Toxic dose 50 (TD50).

INTERPRETATION OF THERAPEUTIC INDEX:  The larger the difference between the two doses, the greater the therapeutic index. In the example above, the therapeutic index is 4 (40 mg ÷ 10 mg). Essentially, this means that it would take an error in magnitude of approximately 4 times the average dose to be lethal to a patient. Thus, the therapeutic index is a measure of a drug’s safety margin.  The higher the value, the safer the medication.

MEDICAL IMPLICATIONS OF THERAPEUTIC INDEX:  The therapeutic index offers the medical personnel practical information on the safety of a drug and a means to compare one drug with another. Because the LD₅₀ cannot be experimentally determined in humans, the median toxicity dose (TD₅₀) is a more practical value in a clinical setting. The TD₅₀ is the dose that will produce a given toxicity in 50% of a group of patients. The TD50 value may be extrapolated from animal data or based on adverse effects recorded in patient clinical trials.

 

RELATED;

1. PHASES OF CLINICAL TRIALS

2. DRUG DISCOVERY AND DEVELOPMENT

3. RANDOMISATION

4.  PHARMACOLOGY AND THERAPEUTICS

REFERENCES

DYNAMICS OF DRUGS AND THE HUMAN BODY

 

DYNAMICS OF DRUGS IN THE HUMA BODY:  Today we are living in a drug World where in more than 99% of medical interventions, there will be introduction of a given drug with an intention to cure the underlying disease.  Day to day, drugs are increasingly becoming available to us in big numbers and we keep taking in drugs in our bodies either traditional or conventional pharmaceutical products as they are being discovered, developed and distributed.  But for a non medical personnel or for someone with little or no knowledge about such substances, less is known about the possible interaction of such drugs with our bodies not even the possible adverse effects or drug-drug interactions that we may encounter.  It will actually Suprise you to know the for every substance we meet, there is a an increasing potential to get toxicity from it.  

There is also constant fear that our incredibly increasing self administration of medical compounds will once cause a bigger burden of disease exaggeration like it has never been before.  This being via introduction of antimicrobial drug resistance and this is a great topic of concern these days.  If you have not been following my articles, you can click on the link below to read more about drug resistance.  Antimicrobial drug resistance, a topic of concern.  In this article we are going to look at the brief goings of some of the most common medications that we encounter on a daily basis, the reason we take them and the possible predictable outcomes of such substances and if possible, the possible toxicities from them.

FORMULATION OF DRUGS:  Drugs are formulated in different ways basing on the systems they are intended to act upon.  Some are formulated as capsules for swallowing, some as tablets, others like suspensions and for topical agents as ointments.  For each drug formulation, there are intentions as to why it was did that way and not in any way should a patient manipulate a drug without prior advice from a trained medical personnel.  Let's say you are give capsules to swallow, it is not advisable at all to open such capsules.  The reason drugs are formulated differently is something to do with their pharmacokinetics and pharmacodynamics which we discussed earlier and if you would like to read more about them, click on the links below.  Any attempt to modulate the drug from it's original formulation will change either it's absorption, distribution of metabolism by the body.  Pharmacokinetics of drugs  Pharmacodynamics of drugs

It should be noted however that, as long as many drugs may be tablets, there maybe their equivalents in syrups, suspensions and or ointments and it turns out that, you only have to use any drug formulation prior to consultation from a trained medical personnel.

ROUTES OF DRUG ADMINISTRATION:  First, before any drug is taken, there must be a specific route it should undertake.  Some drugs are taken via the mouth and we shall later be relating to that as the oral route, other are taken via the nose and we shall be taking that as inhalational route, while for others the drug is injected into the vein and muscle tissue and we shall be addressing those and intravenous and intramuscular route of drug administration respectively. If you have not been following us, click here to read more about routes of drug administration.

Each of the drug routes used during drug administration has a purpose and not at any point a drug should be administered via a non intended route.

MECHANISM OF ACTION:  For any drug, there must be a way it interacts with the human body and or microbes and cause a desire effect, which we sometimes we refer to as the drug's pharmacodynamics.  It is pharmacodynamics actually that gives a clinician the order of writing a prescription.  The mechanism action also helps in understanding the possible side effects, adverse effects and if any the toxic effects of that particular drug and to get details, let us look at a few examples.

1.  An infection by Salmonella bacteria will require a drug that can kill the bacteria and in that case, and antibiotic will be indicated, with it's mechanism of action being bacteriacidal.

2.  An asthmatic attack will mean we are having impared gaseous exchange and in that case one of the drugs to be indicated, will have a potential to widen the brochi, being a brochodilator by mechanism of action.

EXCRETION OF DRUGS FROM THE BODY:  Once taken in and they have finished exerting their effects or reached peak desire concentrations, drugs must be eliminated from the body.  This happens to either the unchanged drug or metabolites and end products of such drugs.  The chief organs and systems that play this role include the kidney that eliminates most of the drugs via the urine, the gastrointestinal tract that eliminates components through faeces, and for some via the skin and respiratory system.

RELATED;

1.  DYNAMICS OD THE HUMAN BODY-SYSTEM MAKEUP

2.  THE INTRAMASCULAR ROUTE OF DRUG ADMINISTRATION

3.  DYNAMICS OF INFECTIOUS DISEASES

4.  THE HUMAN KIDNEYS

5.  ANTIMICROBIAL DRUG RESISTANCE

RIFAMPIN

  

INTRODUCTION:  Rifampin is a semisynthetic derivative of rifamycin, an antibiotic produced by Streptomyces mediterranei. It is active in vitro against gram-positive and gram-negative cocci, some enteric bacteria, mycobacteria, and chlamydiae.

MECHANISM OF ACTION: Rifampin binds to the β subunit of bacterial DNA-dependent RNA polymerase and thereby inhibits RNA synthesis.  We should therefore say it is an antimetabolite but to be precise, it is an RNA synthesis inhibitor.

RESISTANCE TO RIFAMPIN: Resistance results from any one of several possible point mutations in rpoB , the gene for the β subunit of RNA polymerase. These mutations result in reduced binding of rifampin to RNA polymerase. Human RNA polymerase does not bind rifampin and is not inhibited by it.

SPECTRUM OF ACTIVITY:  Rifampin is bactericidal for mycobacteria. It readily penetrates most tissues and penetrates into phagocytic cells. It can kill organisms that are poorly accessible to many other drugs, such as intracellular organisms and those sequestered in abscesses and lung cavities.

PHARMACOKINETICS:  Rifampin is well absorbed after oral administration and excreted mainly through the liver into bile. It then undergoes enterohepatic recirculation, with the bulk excreted as a deacylated metabolite in feces and a small amount excreted in the urine. Dosage adjustment for renal or hepatic insufficiency is not necessary. Usual doses result in serum levels of 5–7 mcg/mL. Rifampin is distributed widely in body fluids and tissues. The drug is relatively highly protein bound, and adequate cerebrospinal fluid concentrations are achieved only in the presence of meningeal inflammation.

CLINICAL USES:  Mycobacterial Infections: Rifampin, usually 600 mg/d (10 mg/kg/d) orally, must be administered with isoniazid or other antituberculous drugs to patients active tuberculosis to prevent emergence of drug-resistant mycobacteria. In some short-course therapies, 600 mg of rifampin is given twice weekly.  Rifampin, 600 mg daily or twice weekly for 6 months, also is effective in combination with other agents in some atypical mycobacterial infections and in leprosy.  Rifampin, 600 mg daily for 4 months as a single drug, is an alternative to isoniazid for patients with latent tuberculosis who are unable to take isoniazid or who have had exposure to a case of active tuberculosis caused by an isoniazid-resistant, rifampin-susceptible strain.

OTHER INDICATIONS: Rifampin has other uses in bacterial infections. An oral dosage of 600 mg twice daily for 2 days can eliminate meningococcal carriage. Rifampin, 20 mg/kg/d for 4 days, is used as prophylaxis in contacts of children with Haemophilus influenzae type b disease. Rifampin combined with a second agent is used to eradicate staphylococcal carriage. Rifampin combination therapy is also indicated for treatment of serious staphylococcal infections such as osteomyelitis and prosthetic valve endocarditis.

ADVERSE REACTIONS:  Rifampin imparts a harmless orange color to urine, sweat, and tears. Occasional adverse effects include rashes, thrombocytopenia, and nephritis. Rifampin may cause cholestatic jaundice and occasionally hepatitis, and it commonly causes light-chain proteinuria. If administered less often than twice weekly, rifampin may cause a flu-like syndrome characterized by fever, chills, myalgias, anemia, and thrombocytopenia. Its use has been associated with acute tubular necrosis. Rifampin strongly induces most cytochrome P450 isoforms (1A2, 2C9, 2C19, 2D6, and 3A4), which increases the elimination of numerous other drugs including methadone, anticoagulants, cyclosporine, some anticonvulsants, protease inhibitors, some non-nucleoside reverse transcriptase inhibitors, contraceptives, and a host of others. Co-administration of rifampin results in significantly lower serum levels of these drugs.

 

RELATED;

1.  GRAM NEGATIVE BACTERIA

2. GRAM POSITIVE BACTERIA

3. ETHAMBUTOL

4.  ISONIAZID

5.  TUBERCULOSIS

REFERENCES

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

 

 

VITAMINS AND MINERALS

 

INTRODUCTION: Vitamins are organic molecules needed in very small amounts for normal body functioning. Some vitamins are coenzymes; that is, they are necessary for the functioning of certain enzymes. Others are antioxidant vitamins, including vitamins C, E, and betacarotene, which is a precursor for the synthesis of vitamin A. Antioxidants prevent damage from free radicals, which are molecules that contain an unpaired electron and are highly reactive. The reactions of free radicals can damage DNA, cell membranes, and the cell organelles.

FORMATION OF FREE RADICALS: Free radicals are formed during some normal body reactions, but smoking and exposure to pollution will increase their formation. Antioxidant vitamins combine with free radicals before they can react with cellular components. Plant foods are good sources of these vitamins.

DEFICIENCY OF VITAMINS: Deficiencies of vitamins often result in diseases including but not limited to: vitamin C deficiency and scurvy, for example. Other deficiency diseases that have been known for decades include pellagra which is due to lack of niacin, beri-beri which is due to lack of riboflavin, pernicious anemia for lack of vitamin B12, and rickets for lack of vitamin D. More recently the importance of folic acid (folacin) for the development of the fetal central nervous system has been recognized. Adequate folic acid during pregnancy can significantly decrease the chance of spina bifida also known as, open spinal column and anencephaly which is the absence of the cerebrum and always fatal in a fetus. All women should be aware of the need for extra folic acid during pregnancy.

MINERALS IN THE HUMAN BODY: Minerals are simple inorganic chemicals and have a variety of functions, many of which you are already familiar with. Among some of the most important minerals we have Sodium and potassium which are very important in the normal functioning of the nervous system and the heart, Calcium important in bone formation, Magnesium and phosphorous as we shall be discussing them in details later.

RELATED;

1. VITAMIN A

2.  VITAMIN C

3.  MAGNESIUM

4.  DYNAMICS OF THE HUMAN BODY

REFERENCES

INTRAVENOUS INFUSION OF FLUIDS

 

INTRODUCTION: When fluid output exceeds fluid intake, volume deficits may result. Shock, dehydration, or electrolyte loss may occur; large deficits are fatal, unless treated. The following are some common reasons for fluid depletion: 

1) Loss of gastrointestinal (GI) fluids due to vomiting, diarrhea, chronic laxative use, or GI suctioning. 

2) Excessive sweating during hot weather, athletic activity, or prolonged fever. 

3) Severe burns. 

4) Hemorrhage. 

5) Excessive diuresis due to diuretic therapy or uncontrolled diabetic ketoacidosis.

PURPOSE OF ADMINISTERING IV FLUIDS: The immediate goal in treating a volume deficit disorder is to replace the depleted fluid. In non-acute circumstances, this may be achieved by drinking more liquids or by administering fluids via a feeding tube. In acute situations, IV fluid therapy is indicated. Regardless of the route, careful attention must be paid to restoring normal levels of blood elements and electrolytes as well as fluid volume. IV replacement fluids are of two basic types namely; crystalloids and colloids.

CRYSTALLOIDS: Crystalloids are IV solutions that contain electrolytes and other substances that closely mimic the body’s ECF. They are used to replace depleted fluids and to promote urine output. Crystalloid solutions are capable of quickly diffusing across membranes, leaving the plasma and entering the interstitial fluid and ICF. It is estimated that two thirds of infused crystalloids will distribute in the interstitial space.

COMPONENTS OF IV FLUIDS: Isotonic, hypotonic, and hypertonic solutions are available for that purpose. Sodium is the most common crystalloid added to solutions. Some crystalloids contain dextrose, a form of glucose, commonly in concentrations of 2.5%, 5%, or 10%. Dextrose is added to provide nutritional value: 1 L of 5% dextrose supplies 170 calories. In addition, water is formed during the metabolism of dextrose, enhancing the rehydration of the patient. When dextrose is infused, it is metabolized, and the solution becomes hypotonic.

EFFECTS OF IV FLUIDS: Infusion of crystalloids will increase total fluid volume in the body, but the compartment that is most expanded depends on the solute in this case, sodium, concentration of the fluid administered. Isotonic crystalloids can expand the circulating intravascular (plasma) fluid volume without causing major fluid shifts between compartments. Isotonic crystalloids such as normal saline are often used to treat fluid loss due to vomiting, diarrhea, or surgical procedures, especially when the blood pressure is low.

Because isotonic crystalloids can rapidly expand circulating blood volume, care must be taken not to cause fluid overload in the patient. Infusion of hypertonic crystalloids expands plasma volume by drawing water away from the cells and tissues.

RELATED;

1.  PLASMA VOLUME EXPANDERS

2.  BODY FLUIDS

3.  ANATOMY AND PHYSIOLOGY

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