By T. Derek. Coppin State College.
Editorial comments • The parenteral form of pyridostigmine (Regonol) is listed with- out detail in the Physicians’ Desk Reference discount kamagra 50mg amex, 54th edition order kamagra 100mg on-line, 2000. Mechanism of action: Antagonizes folic acid, which is required for parasitic nucleic acid synthesis. Contraindications: Megaloblastic anemia caused by a folic acid deficiency, hypersensitivity to pyrimethamine. Clinically important drug interactions: Drugs that increase effects/ toxicity of pyrimethamine: antifolic agents (sulfonamides), anti- neoplastics, radiation therapy, methotrexate, lorazepam. Under such conditions it may be necessary to decrease the dose or dis- continue the drug. Alternatively, it may be necessary to give leucovorin to avoid complications when pyrimethamine is used >3–4 days. Editorial comments • Pyrimethamine is no longer considered a first-line antimalarial agent. The following drugs are generally preferred: chloroquine, mefloquine, sulfadoxine. In such individuals, pyrimethamine should be used with a drug such as chloroquine for 2 days. For chloroquinine- resistant strains, sulfonamides and possibly quinine should be administered with pyrimethamine. Adjustment of dosage • Kidney disease: Creatinine clearance <40 mL/min: initial 3. Onset of Action Peak Effect Duration Within 1 h 2–4 h ≤24 h Food: Administer without regard to meals. Pregnancy: Category C first trimester, Category D for second and third trimesters. Note: Quinidine should be used only for life-threatening ven- tricular arrhythmias. Adjustment of dosage • Kidney disease: Creatinine clearance <10 mL/min: administer 75% of normal dose. Administer with full glass of water on empty stom- ach 1 hour prior or 2 hours following meals. Contraindications: Hypersensitivity to quinidine or related cin- chona compounds, abnormal rhythms due to escape mechanisms (junctional or idioventricular pacemaker), history of quinidine- induced Torsade de pointes, myasthenia gravis, thrombocytopenia associated with previous quinidine administration. It is not advisable to change dosage or discontinue quinidine administration without con- sulting your treating physician. Adverse reactions • Common: diarrhea, nausea, vomiting, fever, rash, anorexia, lightheadedness. Clinically important drug interactions • Quinidine increases effects/toxicity of digoxin, verapamil, depo- larizing and nondepolarizing muscle relaxants, βblockers, warfarin, procainamide, tricyclic antidepressants, phenothiazines, reser- pine. If transaminases increase more than two or three times baseline values, it is best to discontinue quinidine and use a different drug. Quinidine should not be used to treat atrial fibrillation or flutter if these are of longer than 1-year duration. Mechanism of action: Competitively blocks H2 receptors on parietal cells, thereby blocking gastric acid secretion. Cimetidine (another H2 blocker) is considered compatible by American Academy of Pediatrics. Warnings/precautions • Use with caution in the elderly, in patients with hepatic or liver disease, and in immunocompromised patients. Parameters to monitor • Efficacy of treatment: improved symptoms of gastroesoph- ageal reflux or peptic ulcer disease. Editorial comments • Current management of peptic ulcer disease uses diagnosis and treatment of H. Contraindications: Diabetic ketoacidosis, type I diabetes, hyper- sensitivity to repaglinide. Adverse cardiovascular events in clinical trials were slightly higher (4%) compared with sul- fonylureas (3%). Food: Administer on empty stomach at least 1 hour prior or 2 hours following meals with a full glass of water. Warnings/precautions • Use with caution in patients with hepatic disease, porphyria. If such a test is needed, rifampin should be discontinued approximately 15 days before administration of dexametha- sone. Advice to patient • Avoid driving or other activities requiring alertness until full response to rifampin is evaluated. Accord- ingly, soft contact lenses should not be worn during treatment with this drug. Adverse reactions • Common: diarrhea, red discoloration of urine and other body fluids.
Pill worries • Oxcarbazepine may decrease the effectiveness of hormonal contraceptives and felodipine order kamagra 100 mg mastercard. Adverse reactions to oxcarbazepine About 20% to 30% of patients • Tremor who have had an allergic reaction • Aggravated seizures to carbamazepine will experience • Rectal bleeding a hypersensitivity reaction to Less common reactions oxcarbazepine generic kamagra 50 mg otc. Topiramate, a sulfamate-substituted monosaccharide, is one of the newer anticonvulsants available. Adverse Pharmacokinetics reactions to Topiramate is absorbed rapidly and is partially metabolized in the topiramate liver and excreted mostly unchanged in urine. Low Pharmacotherapeutics starting doses and slow Topiramate is approved as adjunctive therapy for partial and pri- dosage titration may mary generalized tonic-clonic seizures in adults and children older minimize these effects. It may Other common ad- also prove beneficial for other types of seizures and as monother- verse reactions include: apy. Serious but infre- 50% off quent adverse reactions include: • For renally impaired patients (creatinine clearance less than 70 ml/minute), the topiramate dosage should be reduced by 50%. The elimination half-life of ethosuximide is about 60 hours in adults and 30 hours in children. It’s Adverse thought to inhibit an enzyme necessary for the formation of reactions to gamma-hydroxybutyrate, which has been associated with the in- succinimides duction of absence seizures. The Pharmacotherapeutics most common adverse In addition to being the drug of choice for treating absence effects (occurring in up seizures, ethosuximide may also be used in combination with val- to 40% of patients) are proic acid for hard-to-control absence seizures. Other common adverse Drug interactions effects include: Ethosuximide isn’t protein-bound, so displacement reactions can’t • drowsiness and fa- occur. Valproic acid may inhibit the metabolism of ethosuximide • lethargy only if the metabolism is near saturation. Sulfonamides Rarely, blood dyscra- Zonisamide, a sulfonamide, is approved as adjunctive treatment sias, rashes (including for partial seizures in adults. Stevens-Johnson syn- drome and erythema multiforme), lupus-like Pharmacokinetics syndrome, and psychot- Zonisamide is absorbed relatively rapidly, with peak concentra- ic behaviors can occur. Pharmacodynamics Zonisamide’s precise mechanism of action is unknown, but it’s be- lieved to involve stabilization of neuronal membranes and sup- pression of neuronal hypersensitivity. Adverse reactions to sulfonamides Common adverse effects of zonisamide in- More serious adverse effects associated clude: with zonisamide use include: • somnolence • Stevens-Johnson syndrome • dizziness • toxic epidermal necrolysis • confusion • psychosis • anorexia • aplastic anemia • nausea • agranulocytosis. Low doses should be tration with meals may decrease the incidence initiated in elderly patients because of the pos- of these adverse effects. Drug interactions • Drugs that induce liver enzymes, such as phenytoin, carba- mazepine, and phenobarbital, increase the metabolism and de- crease the half-life of zonisamide. It’s used as adjunctive therapy to treat certain types of partial and myoclonic seizures. Levetiracetam isn’t exten- sively metabolized; any metabolites that are produced aren’t ac- Adverse tive. The major metabolic pathway is enzymatic hydrolysis, and reactions to metabolism doesn’t depend on any hepatic cytochrome P450 levetiracetam isoenzymes. The half-life is about 8 hours and is unaffected by dose, route of ad- Common adverse reac- ministration, or repeated administration. The drug’s • fatigue antiepileptic effect doesn’t appear to involve known mechanisms relating to inhibitory and excitatory neurotransmission. Pharmacotherapeutics Less common ad- Levetiracetam has several indications for us, including: verse reactions include: • adjunctive therapy for epilepsy in adults and children older than • depression age 4 • pharyngitis • adjunctive treatment for myoclonic seizures in adults and chil- • conjunctivitis dren older than age 12 • mood swings. Drug interactions Sensitivity to Levetiracetam has no known major drug interactions. Antimigraine drugs Migraine is one of the most common primary headache disorders, affecting an estimated 24 million people in the United States. An episodic disorder, mi- graine produces a unilateral pain that’s commonly de- scribed as pounding, pulsating, or throbbing. Other common symptoms are sensitivity to light or sound, nausea, vomiting, constipation, and diarrhea. Researchers believe that migraine symptoms are caused by cranial vasodilation or the release of va- soactive and proinflammatory substances from nerves in an activated trigeminal system. How can you Choice of therapy depends on the severity, duration, and frequen- tell if it’s a cy of the headaches; on the degree of disability that the headache migraine or a head- creates in the patient; and on patient characteristics. They include: • almotriptan • eletriptan • frovatriptan • naratriptan • rizatriptan • sumatriptan • zolmitriptan. Rizatriptan, sumatrip- Sound-alikes: tan, and zolmitriptan have a half-life of approximately 2 hours; al- motriptan and eletriptan have a half-life of 3 to 4 hours; naratrip- Sumatriptan tan has a half-life of about 6 hours; and frovatriptan has the and zolmitriptan longest half-life (25 hours) and the most delayed onset of action. Don’t confuse the Triptan tablets sound-alike drugs suma- All of the triptans are available in an oral form. Zolmitrip- Both drugs are used to tan and sumatriptan are available in intransal forms. The injectable form but recommended dos- of sumatriptan has the most rapid onset of action of all the trip- es are significantly dif- tans. A patient experiencing nau- include: sea and vomiting may prefer injectable or intranasal sumatriptan.
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