Teratogenic effects of the anticonvulsant gabapentin in mice.

INTRODUCTION: We aim to study and elucidate the safety profile of the antiepileptic doses of gabapentin during pregnancy, and to evaluate gabapentin-induced murine fetotoxicity at different dose levels. METHODS: A total of 60 pregnant mice, divided into 12 groups of five mice each, were exposed to gabapentin in four different doses of 0 (control), 113, 226, or 452 mg/kg body weight per day, at three different gestational stages including early gestation (1-6 days), mid-gestation (7-12 days), and late gestation (13-17 days). The pregnant mice were euthanized on day 18 of gestation, and foetuses were examined for teratogenic manifestations. Their brains were dissected and examined for gross changes, malformations, histological changes, and quantitative protein estimation. RESULTS: Foetal resorptions were observed in all treated groups with gabapentin administration at early gestation (1-6 days), and mid-gestation (7-12 days). On the other hand, growth retardation along with stunting in size of live foetuses were observed in all the mid-gestation (7-12 days), and late gestation (13-17 days) treated groups. Various gross malformations were observed with all the three doses (113, 226, and 452 mg/kg body weight per day) when gabapentin was administered at mid-gestation (7-12 days). The same trends were confirmed by gross and microscopic examination of brains along with quantitative protein estimation. CONCLUSION: Gabapentin should not be prescribed during pregnancy, as no therapeutic dose of gabapentin is safe during this period as far as the foetal well-being is concerned.

Lamotrigine in pregnancy: safety profile and the risk of malformations.

The use of antiepileptic drugs in pregnancy always presents challenges to doctors and their patients as it may have deleterious effects on the developing embryo. Lamotrigine is most commonly-prescribed drug among the newer antiepileptic drugs; hence, it has been selected for the present review. A number of studies pertaining to the safety of lamotrigine use during pregnancy have been reported, with differing results. Contradictory results have been reported in animals regarding lamotrigine teratogenicity, and human studies have also proven inconclusive. In many countries, human pregnancy registries are maintained to establish the safety of antiepileptic drugs during pregnancy, as all the different suggestions favour some over others, with specific antiepileptic combinations still being questioned. It is our hope that the present work may integrate the available disparate relevant facts into a directed effort towards minimising the risk of foetal compromise.

A comparative study of long acting diltiazem (Tildiem LA) with sustained release nifedipine (nifedipine SR) and bendrofluazide in the treatment of mild to moderate hypertension.

The therapeutic efficacy of long acting diltiazem 300 mg od (Tildiem LA) was compared with sustained release nifedipine 20 mg bd and bendrofluazide 5 mg od in a multicentre study with 230 patients diagnosed with mild to moderate essential hypertension, with 77, 77 and 76 randomized to the diltiazem, nifedipine SR and bendrofluazide groups respectively. Patients were entered into this randomised, single (investigator) blind, parallel-group multicentre study if the systolic and diastolic blood pressures were > or = 145 mm Hg and/or 95 mm Hg respectively at the admission visit. Twenty-one general practitioners and two hospital physicians monitored patients at baseline and at four and eight weeks of continuous dosing. After eight weeks of therapy, clinically acceptable control of blood pressure was seen in all groups: reductions were 19.2/13.5 mm Hg, 20.4/14 mm Hg and 18.5/10.8 mm Hg for the Tildiem, nifedipine and bendrofluazide groups respectively. Significant differences were shown between bendrofluazide and the other two groups on diastolic pressures (p = 0.01). The non-significant trend was for systolic pressures to mirror these effects. Significantly higher withdrawals caused by adverse events were seen with nifedipine. These were as follows: 14 patients receiving nifedipine (18%), 5 patients receiving diltiazem (6%) and 4 patients receiving bendrofluazide (5%). The difference in this withdrawal rate between treatments was statistically significant (p = 0.01). Post hoc tests revealed that both diltiazem and bendrofluazide had statistically significant lower withdrawals for adverse events than the nifedipine group (p = 0.047). Nifedipine was associated with a marginal increase in standing apex pulse rate and only diltiazem LA significantly maintained serum potassium levels. These results indicate that diltiazem 300 mg is an effective antihypertensive agent and is equivalent in efficacy to nifedipine SR 20 mg and both are superior to bendrofluazide. Nifedipine SR was however the worst tolerated and had the highest withdrawal rate (p = 0.013).

Hypokalaemia in the elderly: is it always diuretic-induced?

Serum potassium was measured within 24 hours in 156 patients (48 male, 108 female) with an average age of 81.9 years admitted to the unit with acute illness. Of the 156 patients, 88 (56.4%) were taking diuretics (none was on ACE inhibitors); 20 patients (12.8%) were also on digoxin therapy. In all, 24 patients (16%) had hypokalaemia and 3 (2%) hyperkalaemia. Hypokalaemia was seen in patients associated with acute illness. There was no significant difference between the diuretic and non-diuretic groups. Monitoring of serum potassium is not routinely indicated to detect hypokalaemia in patients on diuretic therapy except in those with severe hepatic or renal impairment or those on digoxin.

An open study of sub-lingual buprenorphine in the treatment of chronic pain in the elderly.

Fifty-one patients aged over 65 years with chronic pain entered an open study to assess the efficacy and tolerance of low-dose (0.1 mg) sub-lingual buprenorphine administered 3 to 4-times a day over a 14-day period. There was significant improvement in symptoms during the treatment period and the drug was well tolerated, with good compliance. Patients aged over 80 years responded comparatively better than those aged between 65 and 80 years. The incidence of unwanted effects was low and constipation was only reported by 1 patient.