BB = beta blockers, ACEI = ACE inhibitors, ARBs = Angiotensin receptor blockers, CCBs = Calcium channel blockers, HCTZ = Hydrochlorothiazide, CTD = Chlorthalidone, ABs = Alpha blockers, DRI = Direct renin inhibitor
THM 1) List of drugs often used in family practice that can cause HT-
- Cold remedies (esp. containing phenylpropylamine)
- Oral contraceptives
THM 2) Sudden withdrawal of anti-hypertensive drugs can precipitate severe HT. This happens especially on withdrawal of beta blockers & clonidine/moxonidine. A common situation when you will HAVE to suddenly stop a beta blocker is if the patient presents with significant bronchospasm, say due to bronchitis.
THM 3) Hydrochlorothiazide (HCTZ) (‘AQUAZIDE’/’HYDRAZIDE’) if used alone is a weak anti-HT. Often part of combinations. Very cheap (Rs.1/tab of 12.5mg)
THM 4) Examples of drugs within groups-
- BB- atenolol, metoprolol, nebivolol, propranolol, bisoprolol, carvedilol
- ACEI-enalapril, lisinopril, ramipril, perindopril
- ARB-losartan, olmesartan, telmisartan, valsartan, irbesartan
- CCB-amlodipine, nifedipine, felodipine, verapamil, diltiazem
- AB-terazosin, prazosin
THM 5) Concept of ‘Dose Equivalence’ is imp. in HT; eg., 50mg atenolol is equivalent to 100mg metoprolol. Yet most commonly prescribed strength of both is 50mg. Knowing dose equivalence is useful to switch drugs for cost reasons (eg. bisoprolol to atenolol) or side effects (ramipril to losartan if cough) etc.
THM 6) Equivalence of ACEI/ARB is very roughly as follows
Enalapril 5 = Lisinopril 5 = Ramipril 5 = Perindopril 4 = Losartan50 = Telmisartan40 = Olmesartan20 = Irbesartan150
The dose equivalence in dihydropyridine CCBs is approximately as follows:
Amlodipine 5 = S-amlodipine 2.5 = Nifedipine Retard 30 = Felodipine 5.
Diltiazem &verapamil are non-dihydropyridine CCBs. They are also called HRL (heart rate lowering) CCBs. Diltiazem 90mg is comparable to verapamil 120mg.
The 3 diuretics commonly used in HT have following approximate dose equivalence:
HCTZ 12.5 = Chlorthalidone 6.25 = Indapamide (plain) 2.5 = Indapamide SR 1.5
THM 7) All anti-HT drugs are safe in pts. of chronic liver disease except methyldopa & labetalol. In cirrhotics, propranolol can reduce both systemic & portal HT.
THM 8) NSAIDs can blunt the action of anti-hypertensive drugs, especially diuretics, beta-blockers, ACE inhibitors & ARBs. No NSAID is safe in this aspect.
THM 9) Few facts about alpha-blocker antihypertensives like prazosin and terazosin
- Not used as monotherapy as studies don’t show mortality/ morbidity reduction.
- First dose hypotension is a significant side effect of alpha- blockers. Hence start at low dose and build up gradually. Use cautiously in the elderly.
- Prazosin(MinipressXL-expensive, PrazopressXL-cheaper); starting dose 2.5mg OD, optimum 5mg bd.
- Terazosin (Hytrin-exp.,Terapress-cheap)1mg od to 2mg bd.
THM 10) Besides postural hypotension, alpha-blockers can cause tachycardia, diarrhoea & fluid retention.
THM 11) They are principally used as 4th,5th or 6th add-on agents.
THM 12) Prostate specific alpha-blockers like tamsulosin don’t lower BP. Conversely,anti-HT alpha-blockers are as effective as tamsulosin for relief in BPH.
THM 13) The incidence of myopathy with statins is approx 0.1 %. Incidence increases on concomitant administration of fibrates,niacin, erythromycin or fluconazole.
THM 14) Statins are contraindicated in women who are pregnant as cholesterol is essential to foetal development. Statins contraindicated in lactation too.
THM 15) Women desiring pregnancy should stop statins 6 months before planning pregnancy. Fibrates & niacin are also contraindicated in pregnancy.
THM 16) Fibrates like fenofibrate have an interaction with oral anticoagulants like warfarin such that the dose of warfarin needs to be reduced.
THM 17) Omega 3 fatty acids in a dose of 4gm/d can be recommended in pts. with TG > 500mg%. Commercial capsules contain 500mg per capsule. 8 caps/d will cost Rs.50/-.
THM 18) 75 gm/day of almonds reduce LDL by 9% and raise HDL by 4% . But be warned! 75 gm of almonds contain 491 calories!