Introduction to clinical pharmacy

Introduction to clinical pharmacy

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  1 Clinical Pharmacy Clinical pharmacyis a health science discipline in which pharmacists provide patient care that optimizes medication therapy and promotes health, and disease prevention. Clinical Pharmacy includes all the services performed by pharmacists practicing in hospitals, community pharmacies, nursing homes, home-based care services, clinics and any other setting where medicines are prescribed and used. How clinical pharmacy differ from pharmacy? Or Clinical pharmacy vs pharmacy. § The discipline of pharmacy embraces the knowledge on synthesis, chemistry and preparation of drugs § Clinical pharmacy is more oriented to the analysis of population needs with regards to medicines, ways of administration, patterns of use and drugs effects on the patients. § The focus of attention moves from the drug to the single patient or population receiving drugs. Overall Goal of Clinical Pharmacy The overall goal of clinical pharmacy activities is to promote the correct and appropriate use of medicinal products and devices. These activities aim at: § Maximizing the clinical effect of medicines, i.e., using the most effective treatment for each type of patient § Minimizing the risk of treatment-induced adverse events, i.e., monitoring the therapy course and the patient's compliance with therapy § Minimizing the expenditures for pharmacological treatments born by the national health systems and by the patients, i.e., trying to provide the best treatment alternative for the greatest number of patients. § To assist the physician in doing a better job of prescribing and monitoring drug therapy for the patient. Introduction to clinical pharmacy RAYHAN 13 th Batch Pharmacy Clinical pharmacy
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  2 § To assistmedical and para-medical staff and documenting medication incidents correctly. § To maximize the patient's compliance in drug use process. How Clinical pharmacy activities may influence the correct use of medicines? Clinical pharmacy activities may influence the correct use of medicines at three different levels- before, during and after the prescription is written. 1. Before the prescription  Clinical trials  Formularies  Drug information  Clinical pharmacists have the potential to implement and influence drug-related policies, i.e., making decisions on which drugs deserve to be marketed, which drugs should be included in national and local formularies, which prescribing policies and treatment guidelines should be implemented.  Clinical pharmacists are also actively involved in clinical trials at different levels: participating in ethical committees; study monitoring; dispensation and preparation of investigational drugs. 2. During the prescription  Clinical pharmacists can influence the attitudes and priorities of prescribers in their choice of correct treatments.  The clinical pharmacist monitors, detects and prevents harmful drug interaction, adverse reactions ad medication errors through evaluation of prescriptions' profiles.  The clinical pharmacist pays special attention to the dosage of drugs which need therapeutic monitoring.  Community pharmacists can also make prescription decisions directly, when over the counter drugs are counselled. 3. After the prescription  After the prescription is written, clinical pharmacists play a key role in communicating and counselling patients.  Pharmacists can improve patients' awareness of their treatments, monitor treatment response, check and improve patients' compliance with their medications.  As members of a multidisciplinary team, clinical pharmacists also provide integrated care from 'hospital to community' and vice versa, assuring a continuity of information on risks and benefits of drug therapy.
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  3 Pharmacology and Clinicalpharmacology Pharmacology is the study of drugs (chemicals) that alterfunctions of living organisms. Or Pharmacology is the study of drugs - how they interact with other molecules in the body and how they affect the body. This field of study can be broken down into two smaller pieces: pharmacokinetics and pharmacodynamics. Clinical pharmacology is the use of drugs to prevent, diagnose, or treat signs, symptoms, and disease processes. When preventionor cure is not a reasonable goal, relief of symptoms can greatly improve quality of life and ability to function in activities of daily living. Medications Drugs given for therapeutic purposes are usually called medications. Medications may be given for various reasons. In many instances, the goal of drug therapy is to lessen disease processes rather than cure them. To meet this goal, drugsmay be given for local or systemic effects. Drugs with local effects, such as sunscreen lotions and local anesthetics, act mainly at the site of application. Drug with systemic effects are taken into the body, circulated through the bloodstream to their sites of action in various body tissues, and eventually eliminated from the body. Most drugs are given for their systemic effects. Drug names Individual drugs may have several different names, there are two most commonly used are 1. The generic name is related to the chemical or official name and is independent of the manufacturer. The generic name often indicates the drug group. Eg-penicillins, amoxicillin. 2. The trade name is designated and patented by the manufacturer. For example, amoxicillin is manufactured by several pharmaceutical companies, some of which assign a specific trade name (eg, Amoxil, Trimox). Drugs may be prescribed and dispensed by generic or trade name. Testing and Clinical Trials The testing process begins with animal studies to determinepotential uses and effects. The next step involves FDA reviewof the data obtained in the animal studies. The drug then undergoes clinical trials in humans. Clinical trials are research studies that test how well new medical approaches work in people. Clinical trials use a randomized, controlled experimental design that involves selection of subjects according to established criteria, random assignment of subjects to experimental groups, and administration of the test drug to one group and a control substance to another group.
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  4 Pharmacokinetics and pharmacodynamics Pharmacokineticsinvolves drug movement through the body (ie, “what the body does to the drug”) to reach sites of action, metabolism, and excretion. Specific processes are absorption, distribution, metabolism (biotransformation), and excretion. Overall, these processes largely determine serum drug levels, onset, peak and duration of drug actions, drug half-life, therapeutic and adverse drug effects, and other important aspects of drug therapy. Pharmacodynamics involves drug actions on target cells and the resulting alterations in cellular biochemical reactions and functions (ie, “what the drug does to the body”). As previously stated, all drug actions occur at the cellular level. Entry and movement of drug molecules through the body Drugs undergo four stages within the body: absorption, distribution, metabolism, and excretion. After a drug is administered, it is absorbed into the bloodstream. The circulatory system then distributes the drug throughout the body. After the drug has had its effect, then the drug is metabolized by the body. The drug is then excreted, primarily through urine or feces. Absorption Absorption is the process that occurs from the time a drug entersthe body to the time it enters the bloodstream to be circulated.Onset of drug action is largely determined by the rate of absorption; intensity is determined by the extent of absorption. Factors affect the rate and extent of drug absorption, including  dosage form,  route of administration,  blood flow to the site of administration,  GI function,  the presence of food or other drugs, and other variables.
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  5 Dosage Form: DosageForm (DF) is defined as the physical form of a dose of a chemical compound used as a drug or medication intended for administration or consumption. Common dosage forms include tablet, or capsule, syrup, aerosol or inhaler, liquid injection, pure powder or solid crystal. Oral drugs Oral drugs must be swallowed, dissolved in gastricfluid, and delivered to the small intestine (which has a large surface area for absorption of nutrients and drugs) before they are absorbed. Liquid medications are absorbed faster than tablets or capsules because they need not be dissolved. Some patients have difficulty swallowing tablets or capsules; some dislike the taste. In these cases, crushing of medication for powdered delivery (to be mixed with food or beverages) should be considered. But not all medications are suitable for crushing. Drugs that should not be crushed 1. Sustained-release tablets, which can be composed of multiple layers for different drug release times, as can beads within capsules. Some of the more common prefixes or suffixes for sustained- release, controlled-release, controlled-delivery, extended-release, prolonged-release, slow-release products include: 12-hour, 24-hour, CC, CD, CR, ER, LA, Retard, SA, Slo-, SR, XL, XR, or XT. 2. Enteric-coated tablets, which are formulated because certain drugs can be irritating to the stomach or are degraded by stomach acid. By enteric-coating tablets or capsule beads, the drug’s release can be delayed until it reaches the small intestine. Prefixes include EN- and EC-. Advantages & Dis Advantages Sustained-release tablets
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  6 Drug transport pathways Drugmolecules cross cell membranes to move into and out of body cells by directly penetrating the lipid layer, diffusing through open or gated channels,or attaching to carrier proteins. Plasma proteins, mainly albumin (A), act as carriers for drug molecules (D). Bound drug (A–D) stays in bloodstream and is pharmacologically inactive. Free drug (D) can leave the bloodstream and act on body cells. “The liver is the principal organ of drug”- explain. The liver is the principal site of drug metabolism. Drugs can be metabolized by oxidation, reduction, hydrolysis, hydration, conjugation, condensation, or isomerization; whatever the process, the goal is to make the drug easier to excrete. The enzymes involved in metabolism are present in many tissues but generally are more concentrated in the liver. Other tissues that display considerable activity include the gastrointestinal tract, the lungs, the skin, and the kidneys. Following oral administration, many drugs (eg, isoproterenol, meperidine, pentazocine, morphine) are absorbed intact from the small intestine and transported first via the portal system to the liver, where they undergo extensive metabolism. This process has been called a first-pass effect. Some orally administered drugs (eg, clonazepam, chlorpromazine) are more extensively metabolized in the intestine than in the liver. Thus, intestinal metabolism may contribute to the overall first-pass effect. First-pass effects may so greatly limit the bioavailability of orally administered drugs that alternative routes of administration must be used to achieve therapeutically effective blood levels.
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  7 Pharmacodynamic Variables § MaximumEffect аll pharmacologic responses must have a maximum effect (Emax). No matter how high the drug concentration goes, a point will be reached beyond which no further increment in response is achieved. § Sensitivity the sensitivity of the target organ to drug concentration is reflected by the concentration required to produce 50% of maximum effect, the EC50. Failure of response due to diminished sensitivity to the drug can be detected by measuring—in a patient who is not getting better—drug concentrations that are usually associated with therapeutic response. This may be a result of abnormal physiology—eg, hyperkalemia diminishes responsiveness to digoxin—or drug antagonism—eg, calcium channel blockers impair the inotropic response to digoxin. § Drug Clearance is the single most important factor determining drug concentrations. Clearance is readily estimated from the dosing rate and mean steady-state concentration. Blood samples should be appropriately timed to estimate steady-state concentration. § Serum half-life, also called elimination half-life, is the time required for the serum concentration of a drug to decrease by 50%. It is determined primarily by the drug’s rates of metabolism and excretion. A drug with a short half-life requires more frequent administration than one with a long half-life. § Вioavailability is defined as the fraction of a given drug dose that reaches the circulation in unchanged form and becomes available for systemic distribution. The larger the presystemic elimination, the smaller is the bioavailability of an orally administered drug. Receptors Сеll membrane contains receptors for physiologic substances such as hormones (H) and neurotransmitters (NT). These substances stimulate or inhibit cellular function. Drug molecules (Da and Db) also interact with receptors to stimulate or inhibit cellular function.
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  8 Agonists : Agonistsare drugs that produce effects similar to those produced by naturally occurring hormones, neurotransmitters, and other substances. Agonists may accelerate or slow normal cellular processes, depending on the type of receptor activated. For example, epinephrine-like drugs act on the heart to increase the heart rate, and acetylcholine-like drugs act on the heart to slow the heart rate; both are agonists. Antagonists: Antagonists are drugs that inhibit cell function by occupying receptor sites. This prevents natural body substances or other drugs from occupying the receptor sites and activating cell functions. Once drug action occurs, drug molecules may detach from receptor molecules (ie, the chemical binding is reversible), return to the bloodstream, and circulate to the liver for metabolism and the kidneys for excretion. Drug tolerance and cross-tolerance Drug tolerance occurs when the body becomes accustomed to a particular drug over time so that larger doses must be given to produce the same effects. Tolerance may be acquired to the pharmacologic action of many drugs, especially opioid analgesics, alcohol, and other CNS depressants. Tolerance to pharmacologically related drugs is called cross-tolerance. For example, a person who regularly drinks large amounts of alcohol becomes able to ingest even larger amounts before becoming intoxicated—this is tolerance to alcohol. If the person is then given sedative-type drugs or a general anesthetic, larger-than-usual doses are required to produce a pharmacologic effect—this is cross-tolerance. Tolerance and cross-tolerance are usually attributed to activation of drug-metabolizing enzymes in the liver, which accelerates drug metabolism and excretion. They also are attributed to decreased sensitivity or numbers of receptor sites. Adverse effects & side effect of drugs Adverse effects: Тhe term adverse effects refers to any undesired responses to drug after administration. Side effect: any effect of a drug, chemical, or other medicine that is in addition to its intended effect, especially an effect that is harmful or unpleasant is called side effects. Some adverse effects occur with usual therapeutic doses of drugs (often called side effects); others are more likely to occur and to be more severe with high doses.  CNS effects may result from CNS stimulation (eg, agitation,confusion, delirium, disorientation, hallucinations,psychosis, seizures) or CNS depression (dizziness, drowsiness, impaired level of consciousness,sedation, coma, impaired respiration and circulation).
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  9  Gastrointestinal effects(anorexia, nausea, vomiting, constipation, diarrhea)  Hematologic effects (blood coagulation disorders, bleeding disorders, bone marrow depression, anemias, leukopenia, agranulocytosis, thrombocytopenia)  Hepatotoxicity (hepatitis, liver dysfunction or failure, biliary tract inflammation or obstruction)  Nephrotoxicity (nephritis, renal insufficiency or failure)  Hypersensitivity or allergy  Drug fever  Idiosyncrasy refers to an unexpected reaction to a drug that occurs the first time it is given.  Drug dependence  Carcinogenicity is the ability of a substance to cause cancer.  Teratogenicity is the ability of a substance to cause abnormal fetal development when taken by pregnant women. What is clinical Pharmacist? Clinical pharmacists interact, coordinate, and work directly with physicians, other health professionals, and patients to ensure that the medications prescribed for patients contribute to the best possible health outcomes. Clinical pharmacists practice in many different health care environments: hospitals and their affiliated outpatient clinics, emergency departments, community pharmacies, physicians’ offices, community-based clinics, nursing homes, and managed care organizations. Role or functions of clinical Pharmacist? 1. Assuring safe, accurate, rational and cost-effective use of medications 2. Engage in collaborative practice with other healthcare practitioners for the purpose of improving care and conserving resources
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  10 3. Make patient-focusedtransitions into and out of acute care practice settings, ambulatory care or alternative site settings with the patient’s best interest in mind 4. Possess in-depth knowledge of medications that is integrated with a foundational understanding of the biomedical, pharmaceutical, socio-behavioral, and clinical sciences. 5. To achieve desired therapeutic goals, the clinical pharmacist applies evidence-based therapeutic guidelines, evolving sciences, emerging technologies, and relevant legal, ethical, social, cultural, economic and professional principles 6. Assume responsibility and accountability for managing medication therapy in direct patient care settings, whether practicing independently or in consultation/collaboration with other health care professionals 7. Within the system of health care, clinical pharmacists are experts in the therapeutic use of medications 8. Routinely provide medication therapy evaluations and recommendations to patients and health care professionals 9. Clinical pharmacist researchers generate, disseminate, and apply new knowledge that contributes to improved health and quality of life